First: VST is used for digital audio workstations and every big or small studio is using it right now if they have a PC there.
Second: VST-Plugins/Instruments are not the same like OBS-Plugins. They are complex, expensive (and there are some free versions too) and they made by professionals.
A VST is just a format for a plugin. It can be standalone (works just like a usual programm in Windows) or it will need a VST-Host running it.
Believe me, 99% of the music that you are listening to (the last 10 years at least) - pretty much any song have some sounds created by VST instruments or at least the software was used for mixing & mastering the song.
Many of this tools try to copy a well known piece of hardware like the legendary 80`s synthies.
Dont be confused - its complicated because its designed for people who know what they do, but you can trust it, people using this not only in the studio but also live as musicians and DJs - they cant afford a software crash while playing live :-)