Mathematically, a first-past-the-post system will inevitably result in a two-party system (perhaps with the occasional success of a regional party).

There is nothing you can do within the system to change that - you can only vote for the party that better reflects your views (and pressure them to continue to do that).

The thing you do to dismantle two-party politics is advocating for other electoral models: proportional representation; single-transferrable vote or approval voting; etc. 

 If I had to sum up why I continue to read Tumblr in a single post,

https://files.mastodon.social/media_attachments/files/111/160/958/545/023/975/original/8275e39584ead83d.png 

 Has anyone (other than me) proposed making bottom-posting the default when quote-boosts are implemented?

Bottom-posting is IMO the difference between "hey look at this" culture and "yes, and..." culture. It's a small difference, but I think it frames conversations in a very different way. 

 It's amazing how many open source bros will come out of the woodwork to mansplain at you if you make a fairly uncontroversial statement like "it'd be nice if they changed the name of that photo editor to something that wasn't an ableist perjorative", and yet, here we are.