Signal still has a "practical" feature disparity compared to Telegram and WhatsApp. Personally I don't care about many of these newer features, but the mainstream public a lot of times does. Signal was the last one to implement stories and stickers for example, which might seem silly, but I know people who considered this lack as "cons" back then and that got in the way when convincing them to switch.

And for some features it does implement, one can make the argument they're objectively worse than its counterparts. Half the times I tried audio or video calls the lag made it impossible to continue and we had to switch to Google Meet. Likewise, the security feature of the desktop app not retrieving chat histories means that every few months I end up losing it on my desktop or laptop if I log back in after some tie. I put up with that, but because I really like Signal as a privacy-respecting project.

As for a Telegram comparison, their support and features for groups is really unmatched.

I say these things as a donor to Signal, so I really wish this will change, but I have to admit the features arrive late and are still not quite there yet.