For me, the main driver for using c++ with anything is performance. I use Drogon and its exceptional, there is some initial pain when you pick it up for the first time but that's probably the case with Rust alternatives as well. Once you set up and get used to how it works its a breeze to use, the CLI tool makes it easy to add web sockets and controllers, and it has very nice database and JSON integration as well, although I do use Rapidjson for heavy lifting rather than the default.

One of the big gains I have found is you end up with a really nicely structured, rock solid c++ project that is painless to return to even after 6 months, you just pick it up and go. I find coming back to python or javascript projects that I need to sit with the editor open for days before I can get a good handle on things and be productive again. As a solo dev that is important to me as moving between backend, frontend and data tools, you can only can keep one section loaded in Ape RAM at a time.