. is learning the real problem here?
Never underestimate the KISS factor. Analog meters are simple. Then again, I do get a lot of comments from hams about their NanoAntennaAnalyzers. So a few of them are trying to move beyond their Birds....
Of course I have several and some of the local hams did get them during the "craze" when they first appeared. Haven't been on the ham bands in 6 months but I rarely heard anyone speak of using the nanoVNAs for a long time. They know the thing can give a nice sweep of your antenna SWR, but using the other functions such as testing an attenuator or looking at the Smith chart and understanding what it represented - I never heard any of them do it. I really don't think they understood at a basic level what the nanoVNA really was. Basically they think it's a super-cool antenna analyzer.
One older ham that was a friend of mine was given one to use after months of prodding "Hey you gotta check this out!". However he eventually admitted he didn't understand it and didn't want it any more. Said it was too tiny, which I can understand. Yea it can be used from a PC, but that is not up his alley either. 
I have been meaning to get a nanoVNA for some time, but there are so many stories going around about "crappy clones", that it is hard to get a handle on which ones are any good.
Smith Charts?--Yeah, interesting enough, but as far as tuning antennas, if the SWR looks OK, & the antenna takes power, most people will call it good.
After all, it is only in, comparatively speaking, recent years that VNAs were cheap enough for general use in industry---we used Scalar Network Analysers. (Anybody remember the R&S Polyskop SWOB?)
It certainly wouldn't be my instrument of choice for testing attenuators, which can be done perfectly satisfactorily with a signal generator, a 50

termination & an Oscilloscope, or HP410C.(Or, of course, with a Polyskop, if you have one in the garage, "monstering" your car for elbow room!)
Surely "tiny" is the nanoVNA's main strength, in that you can take the thing to an antenna feedpoint, & test it without having to allow for a "longish" feeder.
Dragging a laptop around with you reduces that convenience------yes, I know you can correct for that & measure from inside the "shack", but it is messy, when an MFJ259 lets you do the basic stuff, at the feedpoint in the same way, & is easier to read.
I would have expected the price of secondhand MFJ259s to crash with the advent of nanoVNAs, but that hasn't been the case, so that is definitely an argument in favour of the latter, for those of us without a lot of money to play with.