Csound has a lot of readymade oscillators, filters, and reverbs but most of them sound pretty mediocre, because they're made by academics, not professional plugin developers.

There is a world of difference between a simple four pole filter and a really good juicy Moog filter emulation. Csound has the former, but it only has poor attempts at the latter.

The original point of Csound was to have unlimited anything connected in unlimited ways. But you need a code front end to generate the Csound code to handle any kind of non-trivial complexity, and that's a huge project in its own right.

So Putting Csound into VSTs makes no sense at all. You may as well just write raw C++ and package it using JUCE. The code will be faster and more efficient and just as cross-platform. And if you want to use readymade C++ libraries for basic building blocks they're not hard to find.

Pure data vs Max/MSP is a similar situation. The former is totally free but it simply sounds worse than the latter even with oscillators alone somehow. I think a lot of non-musicians don't realise the huge chasm between a "digital" and cheap sounding thing, and something that sounds warm and full out of the box. It's also just not clear what to do to achieve such a thing generally

You see the assumption is that if you are using Cabbage, you are either learning Csound or you already know it. So Cabbage allows you to sidestep the abysmal arrangement API in Csound for something more intuitive by embedding it in a DAW. But now I realise this makes no sense at all and will advise any hobbyists currently doing this they need to start learning C++ and thinking about cross-platform support.

It makes sense when you don't want to write C++. Also - Csound already has some built-in functions - so you can use them and dont bother with implementing primitives.

it will never be polished like a VST plugin is, written in C++

You think? This looks pretty good to me.

https://www.kia.com/us/en/movement/our-instrument

average plugins for average car buyers