I don't think so exactly honestly. Because if you have noticed so far, top Premier League teams are prioritizing the league title over the Champions League one. This was why Arsenal also couldn't meet the expectations completely in the previous season.
In fact, it is not like what you said, the Champions League is the most prestigious league in European competition, every club that qualifies there will try to compete with other clubs to win the title. If that is true, have you ever seen Areta field a line up containing reserve players last season when they played in the Champions League?
Arsenal failure in the Champions League is not because they did not prioritize the UCL trophy, but because they lost the competition with other clubs. That's the fact.