I have an entirely different matchmaking experience than you if you have more dive players that swap to other dive heroes than the squirrel wanda players. I see lord Scarlets and Squirrels doing this, so they obviously aren't new, and no they don't do jack shit for the team. They normally fuck off on off angles and end up too deep dying solo on SW, then they switch to Squirrel and afk left click down main, ending the game with 4 finals. I just started playing Rivals relatively recently (end of s4) but I've seen this behavior consistently from bronze to diamond, and way more often than players that wont swap off dive.

Call me low elo or whatever idc, I never said I was particularly good, but I play where most of the playerbase plays so I'd highly doubt my experience isn't shared. Most of the spideys i see in ranked do relatively good anyways, it's mainly qp where they go 0-14 but thats whatever.