Comp is already nearly as strict as that, as it should be.
For QP, I think you underestimate just how much of the playerbase this alienates. That is absurdly strict. Like, ridiculously and needlessly strict for a gamemode that has backfill.
“Play the map or be banned” somehow correlates to making people like it? You have a strange way of going about fixing attitudes.
Yeah, there is nothing more fun than after being in a 10 minute DPS queue to backfill into a game that is lost before you even made it out of spawn.
I think that backfilling is a much bigger turn-off than stricter leaving penalties.
If you are unable or willing to play a 5-15 minute round of Overwatch until the end, then don’t queue up for it.
Anyone who gets alienated by that is quite honestly not a huge loss for the community.
Those are the 2 major issues with Paris and HLC:
People love to complain for the sake of complaining.
Just like you identified correctly: They love to be a “martyr” and getting praised for it by other people.
At least the second part is more or less eliminated by giving them a little timeout before they can play the hero again and ruin another match.
When it comes to the first part:
Let people complain - after all that is what makes them happy 
If you are taking away Paris and HLC it won’t take long before they find something else they will focus on - and I’d prefer to not have even more maps deleted.
Neither of those explain Paris’s current QP status though. People are willing to take the consequences, such as they are, for leaving Paris in QP. Nobody praises them for that, and it’s not “for the sake of it” if there are punishments in addition to the wasted queue time.
Your assumption is that it’s a weird unexplainable social construct instead of the much simpler explanation that it’s a crap map that people don’t want to play and they’re willing to suffer consequences in exchange for not being subjected to it. I’m honestly baffled as to why you’re so inclined to forcing it on people - do you not believe that people genuinely dislike it? Is it all just some weird psychological groupthink experiment where everyone secretly likes Paris but society demands that they lose XP and waste their queue times when they queue into it?
Ah, the ol’ slippery slope. Let me ask you this: In the two-three years of Overwatch before HLC and Paris were added, has there been any map that faced this problem? In the year since they removed Paris and HLC, has there been any specific maps that have taken their place?
[DvaDiff] has left the game
People felt confirmed when Blizzard removed them from comp.
It has gotten a lot worse since that exact moment and many people don’t leave because they think that Paris or HLC are bad, but simply because leavers make it pretty hard to even have a fair match on those maps.
Mass hysteria is a rather well explored phenomenon at this point.
I do believe that those people believe that they don’t like it, because they think it is a bad map.
Though all of the arguments I heard so far on why the map is supposed to be bad are either factually wrong or can be applied to every single 2CP map.
Numbani is getting a whole lot of hate and even a bunch of leavers lately, so that is probably the next map in line.
It’s been happening for ages lol. Ever since Paris was released.
This actually just proves that it’s not anywhere near a consensus. Looking at most-hated-map polls, Numbani is probably the 6th most-disliked map. Polls would indicate that it’d be Blizzard World, Anubis, or Hanamura - though they’re completely eclipsed by Paris and HLC.
Point A Paris has defenders highground that gives it a clear and close sightline on all flank routes on the sole, narrow choke. It’s definitely the most oppressive choke in the game. Interestingly enough, HLC features something very similar. It’s slightly better as the choke is farther away. The other two closest maps (coincidentally, the next two most hated maps on any polls that I’ve seen) feature something similar but less oppressive. Anubis, which you can flank to the left, and Hanamura, which you can flank to the right (if they’re holding highground which the tanks rarely do).
The funny thing is that you mention Numbani and it’s another one of the few maps that has a similar mechanic of really good defender’s highground overlooking narrow chokes (though again, there are more options for tackling it).
I’m not really buying that you’ve never seen a single, legitimate complaint about Paris, because I haven’t even gone into point B and how its defense stall potential is unmatched due to the point size, distance from attacker’s spawn, and different areas that defenders can contest from. Really a poorly designed map, but the fixes aren’t all that hard. People have been recommending the Eichenwald treatment to fix point A for years. If they want to remove it instead of fixing the problems, that’s on them, but something needed to be done. Personally the reason that I think they didn’t bother implementing the simpler changes yet it is because they plan on removing all the 2CP maps in comp inOW2.
Temple of Anubis is by far the worst map in the game.