I don't think the decision to wait to call was irresponsible given the circumstances.
What I do think is wrong and have thought so for a long time is states taking weeks to count all the votes. California and New York are the worst when it comes to this, but Pennsylvania was pretty bad this year too. It makes the US look like a banana Republic. The crucial midwestern states were obviously new to this huge number of mail-in ballots, and they need to improve their vote-counting in future elections. Every state should follow Florida's (and Texas's) lead when it comes to counting votes. They prove that you don't need weeks to count the vast majority of votes after an election. Only military, provisional, and other irregular ballots should take that long. It'll depress conspiracy theories of stolen elections and the country will be better off.
Blame the PA GOP for demanding an amendment to the universal mail-in bill in 2019 stipulating counting of mail-in ballots couldn't begin until Election Day.