It's a good question. i.e. if it takes a year to fix all bugs then why does order matter?

The factor he did not mention is that there are unnamed people who see certain bugs and when they see those bugs, they judge the quality of the software to be poor.

Thus, for human reasons you must fix certain bugs first because it makes certain people feel that the software quality is not poor.

OR because certain bugs prevent the system actually doing what it is meant to do .... thus the bugs that result in the system failing to serve its purpose must be done first.