Even Vitalik Buterin is surprised at just how long Eth2 is taking
Cryptocurrency : Vitalik Buterin says the Eth2 challenge goes beyond technical issues
It is a complicated issue as it is with every large update. I don't know if they some problems like Bitcoin and Bitcoin Cash back then? But I would not know why that could be the case.
Whatever but these updates are probably discussed in the slightest detail and I am sure there is no consensus all the time between them. Especially if you consider that the development individually has money at stake, which is good for the community but also leads to discussions because all of those brilliant minds on the Ethereum development team has their own opinion.
But such update shouldn't really be hasten but it's also been a long time since they've promised that update. What's next then? when we're near to said date then they'll extend again? no one knows.