I have personally run converted build systems to Bazel, and use it for personal projects as well.
Bazel 1.0 was released in October 2019. If you were using it "a few years ago", I'm guessing you were using a pre-1.0 version. There's not some cutoff where Bazel magically got easy to use, and I still wouldn't describe it as "easy", but the problem it solves is hard to solve well, and the community support for Bazel has gotten a lot better over the past years.
The difficulty and complexity of using Bazel is highly variable. I've seen some projects where using Bazel is just super simple and easy, and some projects where using Bazel required a massive effort (custom toolchains and the like).
My understanding is that the Python ecosystem is notoriously difficult to integrate w/ Bazel. Javascript is another ecosystem with a lot of fast and loose stuff going on during installs. Golang integration is way better. At work, we use wrappers over bazel (e.g. gazelle) mostly to handle things like auto-generation of BUILD files by parsing source code import declarations and the like. This takes most of the friction away, to the point that many folks don't actually need to understand Bazel to any significant degree.
I think Go works so well with Bazel, because Bazel's concept of versions and modular dependency trees is very similar to Go's.
Python and JS have come a long way in this regard, but depending on the libraries you're using, these languages are still way behind Go/Bazel's standards.
If you're using python, and are scared to jump straight to bazel, poetry is a good in-between tool. More forgiving than Bazel, but strict enough to make a future Bazel migration much less painful.
Bazel 1.0 was released in October 2019. If you were using it "a few years ago", I'm guessing you were using a pre-1.0 version. There's not some cutoff where Bazel magically got easy to use, and I still wouldn't describe it as "easy", but the problem it solves is hard to solve well, and the community support for Bazel has gotten a lot better over the past years.
https://github.com/bazelbuild/rules_python
The difficulty and complexity of using Bazel is highly variable. I've seen some projects where using Bazel is just super simple and easy, and some projects where using Bazel required a massive effort (custom toolchains and the like).