No it isn't. I know someone who runs a specialist news outlet and cross-posts everything to Mastodon. It yields only a trickle of traffic/engagement despite the target market being pretty anti-Musk. Indeed, I'm told traffic/engagement on Twitter has actually improved since the takeover. What people say and how they behave are two different things. A lot of people still check Twitter every day because train wrecks are interesting.

Every time someone shares a link to a Mastodon post, I click on it and eventually realize it's not my instance, so I can't just click to follow the person or return to my feed by clicking. And that is only one example of how the decentralized experience is fundamentally broken.