Its not even just the combo. Both of these champions are so stupid strong. Cait was already doing pretty well before the preseason crit changes, Stormrazer is so stupidly overpowered on crit users.
All season support has easliy been the strongest role in game. (But if you tell a support main that they will 200% disagree).
Pyke specifically is doing more work then a lethality building mid laner - but he doesn't require any gold. Pyke was fundementally unhealthy for the game. Supports shouldnt build lethality - Senna normalized it.
When you look back at the design philosophy behind Rakan, they wanted a support that felt like you were playing an assassin, with Pyke they wanted a support to build the same items as an assassin. I personally think that with how often he gets flexed out of support it should have been enough of an inclination that the support is just miles too strong.
When you have some of the best players in the world like Dopa saying that supports are too strong, its doomed.