Antitrust concerns are reasonably bipartisan. The democratic candidates are getting traction with antitrust platforms because the time is right and they’re the presidential challengers. If Obama was still president, Josh Hawley (for example) would be running a similar primary campaign, with similar success.
I doubt it. As someone outside the US looking in, real rage towards companies like Facebook/Google only really became a mainstream topic after Trump won.
The rage induced by that event got directed at Facebook initially and has now broadened to include all the big tech companies that profit from data collection.
If Hillary had won or in a theoretical world where Obama was still president then talk of breaking up Facebook/Google would still be a niche murmur.