Earlier quoted context omitted.
Signal have a few things that make it a hard sell. It's really hard to clean up media. You have to go into every single chat and from there go about deleting stuff. At least they finally added a "select all" option in there recently. So the size of it just grows and grows and grows until it's using all the space on your phone. Not a good fit for non-technical types. Secondly, no web view. There is the desktop app yes…
It's very frustrating, I admit. Backups and archival are indeed a pet peeve of mine, as are the frequent redesigns (but that's just a "feature" virtually every single god-damn modern app). What is the alternative though? A private chat app, mobile + desktop, syncing, with enough ease of setup and use for normies to adopt? I don't see it.
iMessage, if you only use Apple devices or are willing/able to hack around the Apple-device requirement.