I've a similar problem on Twitter. I don't follow anyone for their political views, so I typically unfollow as soon as I read some but it's far from an optimal solution.
I resisted setting an account up for years on Reddit, but you're absolutely right - it's the only way to effectively filter things you don't want to see.
Same with Facebook. I usually just unfollow people who frequently post political things, but at the cost of missing out on their posts about their personal lives. I wish there was a "subject" filter that I could use to filter out political posts.
Twitter has one I learned recently, but it's pretty enfeebled. It's as far as I can tell, exact matches only, which sounds fine perhaps in the design phase, but was deeply frustrating in practice. There's a new political candidate in America generating lots of buzz who has several permutations of their name (abbreviations and hyphens were my undoing here), so I ended up having to add several entries just to not hear about politics in a country I don't live in!
I resisted setting an account up for years on Reddit, but you're absolutely right - it's the only way to effectively filter things you don't want to see.