If using the default setup of UE (deferred rendering), it results in a shimmering/noisy mess without TAA and TAA introduces a shit ton of blur, so the games end up looking like you have vaseline on your monitor. UE games can still look good if devs use forward rendering, but it requires a bit more work and not using the default setup so they can use MSAA/SMAA instead. Unlikely in bigger games because they want to make them very quick.