I can attest that when it comes to complete migration, bridging is not a solution or at least not a good one. The only way is full adoption.

In my experience, bridging chats moves only a minute fraction of the userbase in the end. The network pull that a userbase migration would make w/o a bridge is highly reduced w/ a bridge and leads to inconvenience for all.

Considering 95% of communication has been text based in my experience, those who were convinced to move to, say, Matrix, moved to matrix but were still able to talk with users who weren't that convinced to move and stayed on Discord. This formed the middle ground to satisfy both sides but this barely did anything in terms of creating a secure line of communication and virtually stopped the transition and also reversed it because of the few inconveniences caused, primarily the inability to join VC sessions across and making DMs across. And of course as you said, sharing links is too much hassle compared to just a click. (Although this is not the case w/ Matrix as its main clients have in-house VC functionality.)

And yes, I agree that it is certainly difficult to move users as some platforms become too tied up with our lives that if you try to leave any of these sites anyway, you get the risk of isolation. I managed to balance it out to an extent so I have not faced such a situation but I certainly got more time to focus on work and other stuff.

At the end of the day it's still a long road till a more libre internet will be mainstream. At least by making small contributions we can still keep the idea alive.