Putting ads for old.Lemmy.world on reddit would make this site perfect.
There is not enough people on this site to properly achieve its purpose which is to post and discuss content. People would flock to old.lemmy.world if it was advertised. Probably seeing proper migration in a few weeks.
I feel like crowdfunding ads to broaden the Fediverse's reach is a strategy that would actually work great for Pixelfed, Peertube, and Funkwhale since they're content focused. But for the forum and microblog like Fedi platforms such as Lemmy it doesn't really make sense they're more people focused.
Reddit didn't need to run ads to get to it's size, the network effect did that for it.
Reddit started in 2005 and actually used bots to give the illusion of activity before it got big, it was a place for communities to have a hub and explore others when nothing like it had existed. Lemmy doesn't have that luxury people who don't like reddit for 1 reason or another will go to Lemmy if they know it exists.