A good article, although obviously there is no one size fits all solution. Sometimes external will still be better, as the shape of your house might require it. There's also historically been some pretty terrible internal antenna implementations, the range on the old Virgin Hub for example was really bad.
Its gotten a lot better since there has been so much focus on MIMO to improve speeds, rather than just pushing the channel width wider, especially as a wider channel width also tends to reduce range.
Ultimately for the best WiFi coverage, you want to be going through as few obstacles as possible. Ideally you'd have an Access Point in every room you need good coverage in, with a signal that doesn't leave that room at all. But few people are willing to run ethernet to multiple rooms or pay for multiple Access Points, so we have half-arsed solutions like wireless MESH.
There's also the fact that in things like desktop PCs, externally antennas are ALWAYS the way to go, as the PC case itself will block too much of the signal. I'm kinda surprised there isn't a market for PC cases with integrated antennas to get the best of both worlds.
