I personally don't think implementation is as enlightening as far as really understanding what the model is doing as this statement implies. I had done that many times, but it wasn't until reading about the relationship to kernel methods that it really clicked for me what is really happening under the hood.

Don't get me wrong, implementing attention is still great (and necessary), but even with something as simple as linear regression, implementing it doesn't really give you the entire conceptual model. I do think implementation helps to understand the engineering of these models, but it still requires reflection and study to start to understand conceptually why they are working and what they're really doing (I would, of course, argue I'm still learning about linear models in that regard!)