The sad truth is that with rasterization every renderer needs to be designed around a specific set of antialiasing solutions. Antialiasing is like a big wall in your rendering pipeline, there's the stuff you can do before resolving and the stuff you can do afterwards. The problem with MSAA is that it is pretty much tightly coupled with all your architectural rendering decisions. To that end, TAA is simply the easiest to implement and it kills a lot of proverbial birds with one stone. And it can all be implemented as essentially a post processing effect, it has much less of the tight coupling.

MSAA only helps with geometric edges, shader aliasing can be combatted with prefiltering but even then it's difficult to get rid of it completely. MSAA also needs beefy multisample intermediate buffers, this makes it pretty much a non-starter on heavily deferred rendering pipelines, which throw away coverage information to fit their framebuffer budget. On top of that the industry moved to stochastic effects for rendering all kinds of things that were too expensive before, the latest being actual realtime path tracing. I know people moan about TAA and DLSS but to do realtime path tracing at 4k is sort of nuts really. I still consider it a bit of a miracle we can do it at all.

Personally, I wish there was more research by big players into things like texture space lighting, which makes shading aliasing mostly go away, plays nice with alpha blending and would make MSAA viable again. The issue there is with shading only the stuff you see and not wasting texels.