Composer required on the Server in case

Not to hi-jack, but I’m curious.

Say I put something together on localhost in May that has dependencies A, B, C
I upload the vendor folder, all is well

Now in July, dependency B releases a critical security update.

I would need to redo on localhost and re-upload the vendor file

But if Composer were on the server, the critical security update would happen as soon as it was released, or just be easier to do?