This is why I prefer web apps over native apps. Web defaults to selectable text and text readable by extensions. I can long press on almost any word and pick "Define" if I don't understand a word (or right click on desktop). Native defaults to unselectable text and no extensions.
It's also why I hate Flutter on web. They render text to canvas, suddenly nothing is selectable and so accessibility and definition/translation options don't work.
See https://earth.gooogle.com Click on a city. An info box pops up. Nothing is selectable. Of course a poorly designed HTML info box could do that too but the designer has to go out of their way to make it bad whereas with Flutter (and native in general) the default is bad.
Everyone in the comments is talking about websites, but TFA is talking about the iOS Bumble app where it's trivial to unintentionally create unselectable text. e.g. SwiftUI Text components are unselectable by default.
Also, in an iOS app, it's common to decide that interacting with some text should do something like navigate.
IIRC tapping a comment in iOS Apollo (defunct Reddit client) would collapse the comment. If you wanted to make a text selection, the Apollo app developer created a specific text-selection-mode for that. That's how anti-user the norms are on native apps compared to the web.
Often, disabling selection on the web comes from trying to port native app norms to a web app.
It's also why I hate Flutter on web. They render text to canvas, suddenly nothing is selectable and so accessibility and definition/translation options don't work.
See https://earth.gooogle.com Click on a city. An info box pops up. Nothing is selectable. Of course a poorly designed HTML info box could do that too but the designer has to go out of their way to make it bad whereas with Flutter (and native in general) the default is bad.