Why do I have to install MSSQL 2016 server?

Hello All,

I have a new windows 2016 server with MSSQL 2017 Server Web edition installed

When installing PLESK, I have to install "MSSQL 2016 server". The option says cannot be removed when I try to remove it.

I assume PLESK wants to use "MSSQL 2016 server" to store databases that let PLESK function. Would it not be possible to just use the already installed instance of "MSSQL 2017 Server Web edition"? Rather than installing a new instance.

(I know I can add the "MSSQL 2017" instance as...

Why do I have to install MSSQL 2016 server?