Sure, you can make plugins for Pelican to make it generate things the way you want, but it's still just a generator/builder using Jinja templates and Markdown or some other text transformation tool.
Also, there's no real indicator that I used Pelican to build my site. There's no cruft I'm including in my <head> element or anything else. It outputs regular-ass HTML.
I'm sure it's nice to be able to swap into dynamic web app mode if you decide a project's going differently than expected, but I don't run into that much with the things I design. I usually know from the beginning which tech I'll need to achieve the goal.
Frameworks force the dev into specific ways of doing things, so if a program fits into that architecture, go nuts. I'm curious what you guys need on your sites that require so much JS.