This could be read as reductive, presumptuous, ignorant, and insulting.

At the same time, it's often technically true, but for a good reason that you neglected to mention:

Those old tools tend to be very capable email clients, not web apps with their awkward attempts to simplify complex conversation structure. A good email client can handle large, high-traffic, frequently branching, long-lived threads with ease. All the web forums I've ever used fail miserably here.

The people who are tasked with participating in large scale discussion groups (like the LKML) know this through experience. They prefer email because it works better. It makes their lives easier. It helps them to be more efficient, which is absolutely necessary given the sheer volume of messaging that they handle.

Yes, a specialized tool is required to get these benefits, just as a specialized tool is required to make web server output easily readable. Thankfully, these tools have existed for decades.