Raids need a solo option.
It’s true that a lot of people still play Pokemon GO, but I don’t see the numbers needed for level 5 raids ever, except from the occasional city trip (~6 hour round trip). Hopefully we will see this soon.
Level 5 raids are the only way to get legendaries, so if you can’t do them, then you will have endless gaps in your Pokedex. This isn’t how the game should be. There should still be advantages to raids for doing them in groups, because that is the point.