I feel like the recent Initiator Tank "Sub-Role Passive" change sorta highlights the flaws of this system.
FIrst up - I like role passives. I don't hate the idea of sub-role passives inherently, but I think they're a weird half-step between addressing the problems individual heroes have vs giving each role a unique identity. Role-wide passives gave each role a strong identity, but did have problems in a lot of cases. Sub-role passives try to address that by being more specialized, but feel like a weird half-measure between role-wide passives and just changing heroes individually IMO. And this recent change highlights that because it sort of breaks the whole conceit of both a sub-role and a passive, doesn't it?
The "Initiator Passive" is no longer a shared ability, nor even really a passive. I understand that before it was too strong and silly to let certain tanks recover HP just by being off the ground, obviously that was more abusable by some tanks than others. But it was created the way it was to keep it consistent between heroes. Now that it's tied to specific abilities, that's no longer the case. There are individual rules for each hero too, like how for Ball you have to reach fireball speed with the grapple to start healing.
Furthermore, and maybe this is petty, but - for these tanks, it literally isn't a passive anymore. You have to actively use an cooldown ability to gain the effects. That was the easiest way for most of these heroes to activate the passive before, true, but not the only way. What we have now isn't a passive, it's just a thing those abilities do now.
And my ultimate point isn't that there's anything wrong with those changes on a balance level. Those changes all make sense and I understand the logic behind them. It's just that maybe it's best we stop pretending there's any common thread? Everything else about this "passive" is already arbitrary and activated a different way on each hero, with abilities that have different cooldowns and requirements to activate the healing. So why is the healing amount the same, at this point? Might as well make it more or less than 50 as needed on a per-hero basis, right? Or is that the only vestige of this being a shared passive that they aren't willing to break?
TLDR: While I understand why the Initiator Passive was changed because it was abusable by certain tanks, when we're at the point that the rules for each initiator have to be specific to that hero, I think it calls into question the usefulness of calling this a "Sub-role passive" at all. It only highlights how arbitrary the "passive" is, as opposed to simply tweaking the individual heroes.