> It's an internet forum, and unlike Twitter and other social media (where I assume they simply have hundreds of mods) they successfully outsourced moderation to volunteers.

This vastly underestimates how much moderating reddit is already doing. When I worked at reddit, we spent at least 50% of all of our resources on fighting spam, harassment, and illegal content. I'm sure reddit is still doing this. What the moderators see is already after the core platform has removed the most obvious offenders. Most of what the volunteer moderators do is remove content that they feel is not in line with their community.

> The customers are the users

The customers are the people who pay, who are mostly advertisers. Customers and users are two different groups with different ideas of what makes reddit good, and sometimes those don't align. It's a fine line to walk between serving the customers and users to try and keep both happy.