After testing in recent weeks, Google Messages is launching the ability to edit an RCS message that you just sent...
This ability to edit RCS — not SMS — is rolling out to stable starting today, but all the Google Messages users in a conversation need to have it enabled.
Yet another W for Signal where you can edit indefinitely, and can look at the edit history. No context lost, no risk of modifying things after the fact
I'm not sure this is a fair comparison, since this is only coming to RCS and not SMS my (completely unsubstantiated) guess would be that this is a message protocol issue.
On the other hand Signal is an encrypted internet messaging service and editing internet messages has been easy for everyone not named twitter for years.
There are ways to do indefinite edits using message relationships
The edit message would simply refer to the message to be edited and contain the new content, or a delta/diff of the content. This would not need to be shown to the user in the UI
The reason it's this fucked up is probably more because it's yet another Google-Specific extension on top of RCS if I had to make a guess.