As someone who has over the last 20 or so years been both a senior front end dev and a designer I don't think this is the case. For me designing in the the browser is fine for details but high level stuff; overall aesthetic, content design, user flow etc. etc. (the primary value of design per se) is better done, at least initially, with dedicated tools. Not necessarily because they're quicker (though they often are) but because different parts of my brain are needed for the different tasks and different tools fit better.
This change to Figma makes me less likely to choose it as my primary tool either as a designer or a developer. Though I guess this is a minority position as I'm compelled to use it all the time as Figma's become a kind of defacto standard in many sectors these days.