"modify" is a very flexible term, but at least Live offers lots of customization options, particularly when you consider Max for Live: https://www.ableton.com/en/live/max-for-live/
If Pure Data was as mature and polished as Max (which it is not) we just as well would.
If not, those things matter more than openness when you have music to record and work to do.
The problem for me is not superior VS inferior or impressive VS unimpressive software but free software VS closed software.
The problem for most people is good and inferior, or "getting my work done with this" and "this is lacking".
Free vs closed doesn't even come second to most people's concerns, and I'm not even sure it should.
My main problem has recently been "why can't I open these songs anymore" vs "can still edit old productions anywhere, any OS, no need for intrusive DRM that takes over my entire laptop just because Steinberg"