Yes, I got a Time Capsule with a nice fat spinning disc, and used its USB port to chain a 4TB HD to it, and have a 6TB networked Plex setup, which was relatively easy to set up and gets me strong dual signal everywhere in my 3 story house. Really impressive tech. The capsule has taken some abuse too and still works. Before that I had an Extreme with basically the same results minus Plex.

It’s not a closed system. So you end up with servicing a not so big product

That's where you want to consider second order effects. The type of person who's buying an Apple Wifi router is probably spending a lot of money on Apple products, it's part of the "long tail". They might be the people most likely to evangelize their products. It keeps expertise about wifi inside of Apple. Getting rid of it seems like a move made by an executive who had to "do something" to look impressive. Apple isn't a cash-poor company that needs to ditch every product that's not part of their core offering. And the Airport wasn't a failed product line, it was a beloved one.

I have a feeling it's more to do with not wanting to help technologically illiterate individuals set up their own wifi, who blame "Apple" when their wifi doesn't work. But of course that's just speculation. The Airport lineup was bar-none the best easy-setup home router on the market when it was pulled.