I suspect that a lot of the "Latin helps you with English" meme comes from the coming together of a couple of things:

1. Some schools wanting to teach Latin at least in part simply because it was part of a classical Western curriculum

but 2. Wanting to justify that inclusion based on more modern practical concerns than it just being something properly educated people learn.

Nothing against Latin or classical Western liberal arts. But the idea that Latin uniquely helps with English is sort of silly.