Personally I don't think Evohome is to blame here, even though the documentation could be better.
It's the whole heating engineer trade which a few present company here excepted, just don't seem to be interested in up-skilling themselves to understand or cope with modern systems. They're too stuck in the old ways of the single simple thermostat in the hallway, a timer and manual TRV's everywhere. Anything else is unnecessary and too complex, to them anyway. If it aint broke, don't fix it...
These people may be good and experienced installation engineers from the point of view of speccing out and installing radiators, pipe work, installing boilers etc, but often lack any real clues about wiring, (beyond wire by numbers in a lego style wiring centre) programming devices like Evohome, (even though they're not really that difficult) and overall systems design of something like Evohome, eg the big picture view of why would you want zoning with electronic TRV's, why would you want OpenTherm and/or Weather compensation etc...
Basically while they may have once been qualified and technically still are on paper, they are for all intents and purposes no longer adequately qualified for the systems that are available today as technology has moved on and left them behind.
When we moved into our current house (which was a bit of a do it upper) the heating system needed immediate remedial work that I was not in a position to do, (and didn't have the plumbing experience at the time for anyway) for example it had no TRV's on any radiators (just on off tap valves!!) many of which were leaking, many radiators had old single end feed fittings that weren't working properly, two radiators had been removed by the previous owners and weren't in service and so on. So I had to get a local guy in to do a bit of quick remedial work such as fitting manual TRV's so the system was usable, whilst already having in mind that I wanted to fit Evohome in the near future.
As part of that I asked them to fit an automatic bypass valve (as I had the intention of controlling all radiators once I had Evohome) and that created a puzzled response asking why I needed an automatic bypass valve on an old system with a bypass radiator... which lead to a conversation about Evohome.
Well, the guy was completely against it - said systems like Evohome were a complete waste of time and I was wasting my money, but simultaneously admitted that he had never worked on one and didn't know how it worked... so, yeah...My attempts to explain the benefits of it fell on deaf ears. I would say the guy was probably in his 50's and his helper in his 30's.
They did a perfectly good job at the plumbing work that they did, but not a clue about something like Evohome - totally outside their wheelhouse.
I've drawn analogies before with the motor mechanic trade which used to be a grease monkey swinging on spanners job. Nowadays while there is still quite a bit of that, the mechanical parts of cars have got a lot more reliable and a lot of problems tend to be wiring, electronics or computer related, with considerable electronic diagnostic skills required - and quite often lacking! That is going to be even more the case with the adoption of electric cars where the majority of faults are likely to be electrical in nature.
I'm not sure what the answer is - perhaps changes to the qualification standards (I have no idea what they are) to bring long time heating engineers up to speed with the current state of the art and perhaps even mandatory re-qualifying to meet the new standards ? Today being a competent heating engineer is a cross discipline multi-skilled job.