I did ask a similar question a bit back here but never really had a satisfactory technical answer. Reading through the documentation of
xdoc Lars Hellstrom pretty much asked the same question and noted in a footnote (page 47),
Seriously, can someone explain to me why it seems just about every non-math LaTeX environment that doesn’t start a
\trivlist? What good does all these
Is it (a) that people just like the basic design, (b) that there’s some deep technical reason, or (c) that people in general doesn’t have a clue but all other environments do that so it’s best to include it just in case?
Can someone explain the technical reasons for adopting such a design and the alternatives?