As someone who learned cursive by learning a new script first, you're making a big assumption here. Nobody learns to not connect their letters.

I didn't learn to not connect my letters. I learned to write without connecting letters, and never properly learned to connect them (until much later in life), because that was never required (and never emphasised while I was in school anyway). If I were to write as I did before, but attempt to connect the letters, it would turn into an unreadable mess. So I didn't. Not until I learned to write in a new script and could transfer that back to my original handwriting. I still don't write a cursive lowercase F, because Cyrillic doesn't have that glyph, and the one that I'm supposed to use never looks right. Not that it matters, since I only write in cursive for myself.