I think this is pretty true, and while the Valkyrie of that incarnation was super duper OP and should not come back, it highlighted what I think Mercy’s current struggle is (ult and otherwise). To be more engaging, she needs to have some decisions to make, which means she needs something to do that is a) possible to do, and b) more valuable than, simply holding LMB on her team.
I think Mercy’s basic healing may still be a hair too low—which is going to be tricky to balance, since her reliable healing means she shouldn’t do huge amounts of it at once—but it is also significant that when Mercy is healing, she can’t do anything else. For her to pull out her pistol, to rez someone, or even switch to damage boost, her team has to be doing okay enough on health that people won’t melt while she’s doing the cool thing.
With OP-Valk, Rez was fast and reliable enough that it was easily worth Mercy’s time to abandon her team to go attempt it. Current rez wastes 2 seconds of healing for Mercy’s entire team if she uses it in Valk, for an ability that risks her life and is not guaranteed to work, and battle Mercy is best used when you need to eliminate a threat you can’t out-heal. Damage boost can only be used if the healing isn’t needed, and healing isn’t enough to keep up with good primary fire from any of the DPS.
This means that healing is the least rewarding, tangibly impactful part of Valkyrie (and arguably of Mercy’s whole kit at the moment), but frequently is too necessary to stop, and ends up taking most (or all) of Mercy’s attention to do.
It can totally be worth going battleMercy with Valkyrie to take out a Widow, because that’s the best way to keep your team alive. But in other circumstances, you get a bigger DPS payoff by boosting your team and letting them do the work. But if your team is taking heat, you have to heal them instead of boosting them.
I think Valkyrie could be versatile and impactful if Mercy can heal while shooting/rezzing/etc. If Mercy’s biggest impact comes from the not-healing part of her ult, but her team needs the healing part of her ult, then it would smooth things out a lot and give Mercy a lot more impact if the healing was something that just happened, through an AoE or an auto chain to the nearest friendly or something. So Mercy would still have to position herself relative to her team, but Valkyrie would turn into “STAND BACK, I’mma do something”, as opposed to “I hope my healing is enough to keep my team up and maybe even do something”.
That might well be super duper OP, and it certainly would be a divergence from Mercy’s gameplay thus far, but it would give her agency as far as when/where/what to do with her ult, as opposed to “use it to boost my team or just go Rambo”