I mean, Doffy just makes strings right ?
It could seems like a really shitty DF with a really shitty user, so i think it's more on Doffy making it great like Luffy with the Gomu Gomu.
Mochi seems better at base since it mimmics a Logia in some ways, though while keeping in mind that Katakuri's CoO is what allows to properly create that ilussion of an "invincible Logia".