The main problem is that Brexit Meant Brexit: the Leave camp was promoting a dozen different and contradictory goals at the same time, and every pro-Leaver was free to cherry-pick their own interpretation of Brexit from it.
This obviously led to a massive issue when they actually won: you simply can't have your cake and eat it - especially when it involves another foreign power! There is no universe in which it would've been possible for the UK to completely detach itself from all EU rules, while still retaining completely free transit of goods, while also taxing import certain goods for protectionist reasons. Similarly it was never going to be possible for UK citizens to retain unlimited visa-free travel to the Schengen area while retaining the possibility for the UK to arbitrarily block access to certain groups of EU citizens.
The most obvious example of this is Northern Ireland: you can't leave the Common Market, and keep an open border between NI and RoI (thus not blowing up the Good Friday agreement and not starting another civil war), and keep an open border between NI and GB (thus not partially giving up sovereignty and suggesting acceptance of a slow move towards a united Ireland). Failing to deliver on all three at once (as promised piecemeal by various pro-Leave people) isn't malicious compliance - it's reality. Something has to yield, and if you don't decide up-front you'll of course get a nasty surprise later on.
This obviously led to a massive issue when they actually won: you simply can't have your cake and eat it - especially when it involves another foreign power! There is no universe in which it would've been possible for the UK to completely detach itself from all EU rules, while still retaining completely free transit of goods, while also taxing import certain goods for protectionist reasons. Similarly it was never going to be possible for UK citizens to retain unlimited visa-free travel to the Schengen area while retaining the possibility for the UK to arbitrarily block access to certain groups of EU citizens.
The most obvious example of this is Northern Ireland: you can't leave the Common Market, and keep an open border between NI and RoI (thus not blowing up the Good Friday agreement and not starting another civil war), and keep an open border between NI and GB (thus not partially giving up sovereignty and suggesting acceptance of a slow move towards a united Ireland). Failing to deliver on all three at once (as promised piecemeal by various pro-Leave people) isn't malicious compliance - it's reality. Something has to yield, and if you don't decide up-front you'll of course get a nasty surprise later on.