This opinion seems bizarre to me. You start by offering personal (and valid) anecdote, then end up saying "I don't think you can develop [...]". But this flies in the face of evidence. Most people by far do not use your preferred monitor setup (iMac 5K) and in my country a vast number of developers use 1366x768 to develop all sorts of high quality software.
It's one thing to say "as I grow older, I find I prefer $SETUP". No-one can argue with that, it's your opinion (and it might very well become mine as I grow... um, older than I already am!). It's an entirely different thing to claim, as you do here and I think TFA does in similar terms, "you cannot prefer lower tech setups", "you cannot develop software this way", "it's very difficult to develop software without $SETUP". The latter is demonstrably false! I've seen it done, again and again, by people who were masters at their craft.