Because they mimic their voters.

Because it is a communication channel that people still extensively use. Some politicians not using it just disadvantages them.

The only way is to create an even playing field by banning the use of the platform.

Ask them directly

FOMO and FOOPMO

(Fear of other people missing out (on what they have to say.))

Not wanting to piss off the US is a big part of it, I would guess.

Because it’s a huge platform?