I haven't explored Sails enough to know what you're talking about but it might be possible form what I remember. :)
LoopBack does bring a few things that you'd have to manage yourself with Express + Mongoose, like sending the right error codes to the client, modular type checking and multiple datasources (files, MongoDB, MySQL, etc.).
There's actually not that much overhead compared to Express (though it might seem like it at first), and it comes from the same team so it's pretty well integrated and you can still use Express if you need it.
Mongoose is also very strict sometimes and that can lead to some headaches. For APIs, it might sometimes be easier to have a more permissive checking (LoopBack has different settings, so you can adjust that).
Anyway, just sharing a tool, not trying to force anyone to convert to any religion. 🙏
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