To be fair, it once was the best model we had, before we figured out quantum mechanics. That brings up an interesting point, though: the way many of these things are taught closely mirrors the history of how we discovered them in the first place. This is definitely not a coincidence, but I'm also not sure whether it is the most effective way to teach.
In GCSE Chemistry (taught to 15-16ish year olds), we were taught that the first shell contained two electrons, and subsequent shells contained 8 (up to the final, which may contain fewer).
Then, after GCSEs, during A-levels, we were told (by the same teachers, in the same classrooms) to forget this model, and that the situation was actually more complicated, with s, p, d, f orbitals etc.
I realise that this is was a simplification and not necessarily an outright lie, and can understand why they did it this way. But it was the first time I realised I’d been deliberately taught something that was incomplete or inaccurate.
