VS MEF VS Scrutor

This is good info! I had not heard of MEF being split up like this. Looks like there's a full explanation of everything here: https://github.com/microsoft/vs-mef/blob/main/doc/mef_library_differences.md

You can with MS's default DI as well via scrutor.

if you are heavily invested in autofac you can replace the build in DI with another container. at this point i don't think it is that necessary. especially if you use scrutor. it gives your some nice assembly scanning registration that autofac/simple injector give https://github.com/khellang/Scrutor

If you wouldn't mind, I have one additional question. If I wouldn't bother to remove this loading, how could one add that as service when using DI? I have found tool called Scrutor (https://github.com/khellang/Scrutor), is it something commonly used in situation like this?

I much prefer using Scrutor and asbly scanning myself. https://github.com/khellang/Scrutor

you can also use Scrutor to get closer to Autofac functionality https://github.com/khellang/Scrutor

That can't be the only justification, because you can easily register services using reflection without using MediatR.

I might suggest additional registration time extensions to modify the behavior as needed on classes. Take a look at Scrutor for some inspiration on API specifically.

There is a package that simplifies it for you if you want. But not everybody agrees that automatic registration is good pattern, so you have a choice.