I guess if you trust DropBox and Overleaf with sensitive data but not Google Docs or Microsoft Office 365, that works. (If Overleaf is self-hosted, please disregard that part.)

I also find offline word processors frustrating to collaborate on, but I am worried that OP is rationalizing their personal preferences post-hoc, rather than looking for the best option for everyone.

Thanks for the pointer to Overleaf, I will definitely check it out.

Edit: sorry, I thought you were the OP at first.