Well that’s what I mean by “good faith participation” — usually that includes showing off what you are doing/creating to a community you are a part of.

The problem, that you acknowledge, is that some businesses (in reality a majority) do purely advertisements. It is indeed a slippery slope.

However, I’ve seen small businesses/individuals post content that gets praised by the general population of a community and then people start asking “Hey, where’d you get that? Where can I get that?” And then the OP is like “Well I actually make it myself, I sell them as a business but also engage in the hobby myself”. THAT is the most successful way I have seen a business interact in an online forum.