That's not my experience. There seems to be subreddits on every conceivable topic, and you can subscribe to whatever variety you want and you'll get a wildly varied range of views/politics/whatever.
There are even 'change my view' type subreddits for people looking to understand and debate the 'other side' of their arguments.
The comment you are replying to becomes more valid the larger the subreddit regardless of its subject. You wouldn't think subreddits like javascript and programming would be hotbeds of rampant emotional insecurity fueled by deep echo chambers, but they certainly are.
There are even 'change my view' type subreddits for people looking to understand and debate the 'other side' of their arguments.