For me, modular isn’t entirely about the sound. You can get most of the sound possibilities of modular elsewhere. It’s about the workflow: I find it way easier to actually make music & finish tracks on a modular, and I much prefer the modular workflow to a series of hardware boxes awkwardly connected via midi (or to making music itb, which I find incredibly difficult and annoying). Also, it’s fun! Sure, I can get many of these sounds from VSTs, but that’s no fun. Why do this if it’s not fun?
Having said that, there are some things you can easily do in modular that would be annoying in other formats. I’ve recently gotten really into sequential switches (including audio rate switching), and although it’s possible to do this kind of thing in a non-modular setting, it’s a lot more time-intensive to set up. In general, plugging audio rate modulation into anything and everything is a really fun part of modular! There are also some modular oscillators (eg Kermit mk3) that don’t really have any analog elsewhere.