Trunk-based development = putting unfinished work in the team's shared branch.
Feature-branches = finishing your work first.
Anyone who's ever completed a complex PR knows how much plans change over the course of the work. Obviously those immature stages shouldn't be shared with the team, let alone be in main, whether behind feature flags or not.
The draw of feature branches is the same draw as quarterly or yearly releases: People don't know how to decompose problems into stand-alone subproblems that they can tick off one at a time. The solution is the same here. Don't avoid decomposing problems. Do it every week until you figure it out.
However, trunk-based development allows high-paced development of applications, and testers can easily review the combined result on a test environment.
I know some people are diligent about using rebase to present a clean commit history, but that's rare in practice in my experience. And it's incompatible with devs who aren't skilled at git.