VSTi in audacity

Why VSTi is not supported in audacity

Because no-one has added VSTi support.
Adding VSTi support would be a big job. Audacity is open source and volunteers are welcome.

Can i make a quantizer in audacity?
(quantizer means quantizing audio in timings 1/4 1/12 1/24 1/16 etc in MIDI Tempo)
Sorry if having any mistakes