Addressing the first one… Partially because I am feeling a little bit lazy at this time, partially because I stated it beautifully back on August 12th, 2017, I am going to quote myself from the old forums when I discussed “hide and rez”:
“It’s just hide and rez.”
This quote illustrates that the person saying it has no idea what they are talking about. No, it’s not an oversimplification, it’s just plain wrong.
“Hide and rez” is a great strategy… assuming your goal is to get wiped after the resurrection. Hiding turns the fight into a 5v6 with a main healer down. Any competent team would be able to walk through your team without expending ultimates, except to counter any ultimates expended by your team. The enemy team already has the positioning advantage and the first shot after the resurrection. “Hide and rez” would also give them the advantage of more ultimate abilities. Doing so sets your team up for failure.
A good Mercy sustains her team until they can no longer be sustained, or until she can no longer do so safely. By doing this, she allows the team to bait more ultimates before dying, giving your team the ultimate ability advantage after the resurrection.
A team playing against a hiding Mercy would have a significantly easier time dealing with the opposing team, as Mercy is putting her own team at a disadvantage. It wouldn’t even come down to being aware enough to consciously notice the 5v6 (although most players should be able to recognize a 5v6 when they see one), but a matter of knowing how much force the team needs to apply to overcome a given resistance; if the enemy is crumbling, don’t expend limited resources to push a structure that will fall on its own.
Because the opposing team is already at a numbers disadvantage in the initial fight, pushing into them without using any ultimates, except to counter ultimates expended by the enemy, will be sufficient for eliminating the opposition. This further leads to more loaded ultimates, as killing 4-5 enemies in a 2-2-2 composition is roughly equivalent to 1500 charge in HP. That is also excluding additional charge gained through allied healing and allied damage through enemy healing. Combine this with the absence of a need to expend ultimates, and the team with the hiding Mercy is revived looking down the barrel of an incredibly large gun, has no time to draw their own, and is in a poor position to capitalize on it even if they did have the time to draw their own.
As a result, hiding prematurely was detrimental to the team’s chances of winning the fight in the long term, even if it was riskier in the short term. It was a misuse of an ultimate.
To add some perspective to this, using “hide and rez” as a reason to remove Resurrect as an ultimate is about the same as using the fact that some Pharah players Barrage themselves on occasion as a reason to remove Rocket Barrage