This is fairly recent bird lore. Like late 80s to 90s. It takes a while for schools to catch up so I missed it as well.

Dammit, it had to be the only good floss.

Most oat milks now include emulsified lipids for this reason. Oatly foams up to a head better than whole milk. You can’t make butter out of it, but I doubt you’re making butter from your milk at home anyway.