I think it's fair enough. If they accept your spam then they have to accept everyone else's spam too. No it doesn't make any difference that your stuff is free. Reddit subs are usually for discussion not marketing; there are channels to spunk your adverts down and you should use those instead of trying to insert them into discussions. No it doesn't make any difference that your free stuff means you don't have a marketing budget. We all know today's free stuff is tomorrow's subscription stuff, and yeah I can already see you're about to scream at me that you don't ever intend for that to happen. But the simple fact is if your stuff takes off then you're going to have to make more time for it but free stuff isn't going to pay your bills and you're going to have to start raising cash one way or another.
What you should be doing is to continue being a positive contributor, and put your promo stuff on your "about me" page. Anyone who is interested enough in you will look at your profile, see your stuff and maybe then consider engaging with your products.
Forget the 10% ratio, remember the rule NO MARKETING, and then everyone will be your friend again. The 10% rule is not intended to say "you can spam this much and no more", it's to allow people to talk about actual products they like (that others have made) and point to them without those pointers being misconstrued as promotion.
"...votes..." No, the rules are for preventing spam, the voting is to highlight high quality posts over the low quality stuff.
"...billionaires..." What an odd strawman. Business of all sizes from freebie shops like yours up to Microsoft are NOT ALLOWED TO SPAM chatrooms. You're likely to see more stuff about billionaire businesses simply because they're bigger, not because they have some privilege you don't.
I mean come on, there are enough fucking adverts everywhere without discussion groups being full of that shite too. Advertise in advert channels. Chat in chat channels. Don't mix the two. Of course you're proud of the stuff you've made and that's a good thing, but there is a time and a place for promoting it and that place is NOT a discussion group.