For one thing, imagine police responding to an incident at a known leftist coop vs just a regular old pillar of the community main street shop. How are they going to act? Or imagine how much more sway your voice has at city council meeting as a successful small business. Business owners are practically part of the capitalist priesthood, so you're negating one of the biggest advantages for not a lot of gain. There are lots of other reasons, for example I think a day will come when we can use legitimate looking businesses to help people immigrate to countries that are better suited to withstand climate change, ostensibly for the purposes of labour.

A big reason why they degrade and de-radicalize imo is that they're often started and operated by (trying not to be sectarian) consensus obsessed folks. While consensus is great, a more democratic centralist approach is probably best for the sake of efficiency. Basically coops are efficient because they're horizontally organized and don't need a heavy management layer, but then that's negated by having to hash out every single decision ad nauseam.