Benefit of aliases versus custom domain

[TenFour]

d) a bunch of addresses/aliasses not at a known forwarding service for varying degrees of obfuscation.

Why worry about a "known forwarding service?" I use DuckDuckGo addresses a lot, and I find that they work with most services--I think one or two have turned them down. Most people I give a DDG address to in person don't even blink and eye, especially because my main DDG address is a regular word.