I'm actually still jaded about this. Messenger worked fine before they broke it by introducing E2EE; it took years for them to fix the problems this caused (at least the ones that were immediately user-perceptible).
"Let's take people's years-long history between each other and just utterly break it. Why? 'privacy'" but they've never cared about it, they're opportunistic fucks. It's Zuckerberg's company to do with it "as he wishes" https://news.ycombinator.com/item?id=16770818