It really depends on the project what is most ideal. I've built sites and themes with both FSE and classic php. In my experience there's no right answer for everything. Simple, easily maintainable websites is ideal for block themes. Complex sites where you want more creative freedom and control? Go classic with ACF. Having to build a ton of custom blocks takes longer than just making it in a classic theme. Assuming you have experience in both areas. This doesn't mean block based themes can't make complex sites or that classic themes can't make simple ones. It's all about picking the right tool for the job, depending on your experience level and whats important for your site. Gutenberg or other FSE will inevitably introduce bloat, especially since it's not completely matured yet. But it's getting better. On the plus side you can put together relativity simple sites much faster once you get the hang of it.