Companies definitely astroturf on Reddit, but, they do it through third or even fourth parties. There is a whole micro industry of vote buying and comment spamming, ad firms or companies will pay such groups to add certain messaging to their comment spam. You can actually make a quick buck by selling any old Reddit accounts to such groups.
oh yah, I remember the absolute torrent of crypto shills that started spamming the place when crypto shill posts from other subs started getting posted there.
They were proper angry that they got called out.