https://archive.md/BQ3Iq
Another piece on this topic from The Athletic, not earth-shattering but it's worth a read.
One more very obvious point as to why it's different for keepers—for any other position, it is possible to accommodate many more options than just "it's him or him (or him)".
For instance, with our current squad we can readily play any two out of Gabriel, Saliba and White across central defence and have a great defensive pairing, so if Gabriel is dropped, he has many other ways to consider it than "I've been judged inferior to Saliba". Same goes for our options for a midfield trio or across the forward line, not to mention all the other options so carefully engineered into our squad.
Not so easy for Ramsdale and Raya, because an XI only has one goalkeeper on the pitch to whom different laws apply.
Anyway, Arteta implies he's going to rotate and substitute Raya and Ramsdale and it's gonna be interesting seeing how the approach works. If he rotates the two or makes substitutions "between the 60th and 85th minute" as his presser after Everton suggested, and we see an improvement in overall results, it'll be impressive stuff. Otherwise he's just signed Ramsdale's replacement, and dropping a £30m bag is not an innovation in today's football.