Multi-user only require you to use a launcher and has no effect between paraview or vtk.
I’m not sure which part of the previous post made you think ParaView will have an edge on VTK for it.
Maybe the ground of that was because we already have docker images that bundle apache/launcher/pv and we don’t have something equivalent for vtk. But that just so you can run a command line with docker and you have your multi-user setup done. For VTK, you are left configuring and installing all those pieces on your own. But nothing wrong in doing so.
The key difference with VTK and PV on the server is the fact that you will rely on Proxy/ServerManager with PV. This tends to do a lot for you automatically and in a simpler manner (less python code) than in pure VTK. But technically, underneath, it is the same. If you are comfortable with VTK you should not fear doing a vtkWeb application like you just did. Especially since PV is much bigger than VTK.
HTH
Seb