One reason (not the only reason) why I see people sometimes hesitating to switch more fully to Signal, is that they got into a habit of using Signal as their "high-priority, clutter-free" inbox and Telegram as their "everyone else talk to me" inbox, and thus hesitate to make Signal "cluttered" again.
Things that I find work for me in this situation is:
* Signal now has a folders feature: you can right-click (if on phone, tap-and-hold) on a contact and an "Add to folder" option appears
* Using *another* app (eg. Session, Simplex) as your high-signal inbox, this way support projects that are trying to achieve even stronger privacy properties
Also, start to build a habit: when someone contacts you on Telegram, ask: "are you on Signal? I am <username> there", and move that conversation over to Signal.
