Lemmy

I think it's more of people wanting to stick with the developers and apps that they have used on reddit. Some of which have been using and supporting for almost a decade. It also means more of an endorsement for Lemmy, as some reddit sync users wouldn't consider Lemmy otherwise. Lastly, a significant number of power users (those that actually post, comment, and otherwise contribute) use third party apps over the official app, meaning that having support for these apps on Lemmy will hopefully bring over quality users and not just a larger quantity users.

That's my take on it, and I am someone very pro open source.