Sure, it's rather subjective, but I would argue that the majority of people, especially the regular "testers", when seeing the word "steam", will prefer to comment on something else instead (Because of the "if it's on steam already, it does not need
my feedback as much as something else might" impression.), so the advice seems fully valid to me. One almost wants to ask a question - if you are advertising yourself
on a fucking Steam, then why the hell are you even here?
(To get even more publicity? Sure, that is alright, do that, but don't expect to get priority testing when there are games that
noone has played yet, still waiting for their very first feedback... even when the assumption "steam = some players there already" is wrong)