No, they don’t. Generally they don’t have to entirely replace baseline elements with something less capable. Like I said the only example of a node actually changing to a different ability (not the same effect triggering from different spec abilities) is Mage, and that’s just a case of three different flavours of the same ability. There’s no inherent loss of capability when speccing into something. Remember that SL restored the spec model of not having a spec before level 10. When I pick a spec at level 10 it should not feel like the spec is suddenly working against the foundation set by that point. I don’t feel that for any spec other than Survival, because Hunters start with ranged weapons while Survival asks you to throw it away.
Yes Blizzard thinks it’s important but as we have seen from these past few years Blizzard is often mistaken.
Survival Hunters bleat in every other thread about how calling Survival a melee spec is a “meme” and it’s “effectively a ranged spec” so spare me the talk about the melee distinction being important anymore. It’s entirely tokenistic at this stage and brings no value to the spec or the class. In fact it detracts value.
False equivalency is becoming a pattern in your posts.
All of those examples add to their class foundation. The only specs that are comparable to SV are a) Enhancement and Feral due to being melee alongside a ranged spec in the same class and b) Marksmanship due to Lone Wolf. In the case of Feral and Enhancement, both of those classes are structured to support a melee spec a lot better. Druids have shapeshifting and Shamans have a melee weapon by default. And in the case of Marksmanship the only thing that makes Lone Wolf acceptable is that sometimes dependence on a pet is literally a drawback. As for ranged weapons and Survival: ranged weapons are literally never a drawback so it makes zero sense to have a class that’s based around ranged weapons but can spec into not using them. It’s speccing into a handicap and that defies basic spec design. The only way to make it make sense is to either a) make ranged weapons sometimes a drawback again just like before MoP (i.e. minimum range) or b) make Hunters by default a melee class that can spec into being ranged with either BM or MM. Both are terrible ideas.
This is why something like a melee Hunter should be an optional subspec within an existing spec (ideally BM) rather than a separate spec.
I actually do prefer Trick Shots because Bombardment was boring and useless, but the SV one is not the same. It’s not Multi-shot: it’s a dimished melee “equivalent” (not really because it has a CD). Spreading Serpent Stings with Multi-Shot was fun and fit the spec really well, especially since Serpent Sting was highly buffed as SV including an initial tick (which they abruptly and inexplicably removed right before announcing melee SV 
). CDR on bombs is fine, especially since Wildfire Bomb is the only good thing to ever come from melee SV, but having such an ability which is ranged and ill-fitting of a melee spec get its CDR from a generic melee cleave is silly. Ideally we would have a spec focused entirely around that munitions aspect with explosives/poisons etc. and not tack on pointless melee elements or BM ripoffs.
This was also a mistake. Not being able to deal light damage instantly felt bad. The current model is better (barring the tier set) where Aimed Shot has a cooldown with charges so Arcane Shot exists and is still relevant.
Starting off Hunters with Arcane Shot and Steady Shot and augmenting them or replacing them with better abilities is fine. What they shouldn’t be doing is replacing them with worse abilities depending on spec e.g. ranged abilities with melee ones. This still applies even with the SL model where they keep those two ranged abilities in the spellbook but make sure you’ll never use them, which is functionally the same as it was before.
All Hunters should have Arcane Shot, Steady Shot, and Multi-Shot baseline and they should add to those or replace them with better equivalents (e.g. how BM replaces Steady Shot with Barbed Shot) while also adding plenty of unique mechanics to make a distinct identity and playstyle. BM and MM are already mostly there. SV is the odd one out that still doesn’t really fit the class.
No, they just need to all use a ranged weapon. The class needs a core identity again. Look how different BM and MM are right now yet they both use ranged weapons. Don’t pretend there’s no other way to approach it. We have like 6 different varieties of physical melee in this class including an entire pure DPS class (Rogue).
They shared abilities back then because Blizzard first and foremost designed the class and then the spec on top of it, which was actually the better approach. They still do that for BM and MM. They even added Kill Shot back to all 3 specs to reinforce that. Nevertheless they did meaningfully diverge in each expansion and we did have 3 distinct options even before SV was melee. Being melee is not an absolute requirement for SV to be distinct. That’s just tokenism.
Also all classes shared talents back then so it’s a little weird to use this as a jab at Hunters. Yeah it was less variety but at least back then they kept talents balanced so there was actually choice, compared to now where they are hopeless at it and just about every spec devolves into a set cookie-cutter build.
This is just a strawman. What I’m saying is that there should be a better balance between class identity and spec identity. They can’t go all the way to class identity to the point where specs make little difference (e.g. classic WoW) but they also can’t make every spec so separate it feels like a different class with little in common (Legion). SL fares better than Legion in this regard but MoP fares better than SL. Ideally they would take the best of MoP/WoD Hunter and build on that, which is what they should have done back in 2016 instead of the nonsense failed approach they did take.
On a final note: at the end of WoD we saw borrowed power that made Black Arrow have a CDR for SV enabling us to multidot with it and funnel the extra Lock and Load procs into Explosive Shot. That was a pretty cool idea that would have been a great foundation for a future ranged SV beyond that point. Would a spec based around multidotting like that still be a Marksmanship clone in your eyes? Would it be less valuable than being able to restrict ourselves to melee in an otherwise ranged class that’s fully capable at any range?