It’s one of those questions you know you’re going to have to answer the instant you fall in love with the genre. Back in 2011 when “Just Glue Some Gears On It (And Call It Steampunk)” came out, (https://www.youtube.com/watch?v=TFCuE5rHbPA) it was generally accepted as a science fiction subset, consisting of retro futuristic aesthetic, based primarily on the fashions and technologies of 19th century Britain.
If you do a Google search on the phrase “what is steampunk” today, you will get the following definition:
a genre of science fiction that typically features steam-powered machinery rather than advanced technology.”
People actually argue about what is and isn’t steampunk. Viciously.
If steampunk can’t be steampunk in a jeans and graphic t-shirt because the fashion is all wrong, then a costume inspired directly by that fashion should feel just at home within the genre as the one with a mechanized arm. Elitist thinking and actions cast a dark shadow on all of us, so that we all look equally shady by association.
It discourages the newcomers and the curious, and it pushes away the shy and unsure.
Worse than that, it prevents the movement from evolving and growing.
All steampunks are created equal. The only way to do it wrong is to be a jerk about it.