[pbecotte]

This is only true in the limited case where you never have to share your code with anyone. If you want to share it, setting it up so others can get going without having to figure out which packages are missing is necessary. In that case, you should probably use that same tool yourself to make sure that your environment works the same as you expect others to use it.

[mixmastamyk]

Nope, share code all the time. That is what requirements.txt (and alternatives) are for. Where they install them is up to them.