Re: Probably a license issue
To be fair and clear, it isn't Free Software projects that stop themselves from going into iOS, it's Apple who has a political axe to grind against copyleft.
So, you are allowed to access Apple's users only if you remove all your protections and open yourselves up to abuse from those with power. This is because they see Free Software as an unenclosed field ripe for a few fences, and hate the idea it's not untamed wild, it's well regulated commons.
Anyone with an apple device must accept they're under the hegemony of a company that sells paternal coddling, and choosing a strict daddy who won't let you play with the kids next door is not the fault of the kids next door no matter how unfair it seems to you.