Arsenal eliminated from the FA Cup reduced the number of competitions they participated in, the Arsenal could focus more on the EPL and UEL as targets to be achieved at the end of the season. Arsenal also avoided a busy schedule that often injured players due to fatigue. Arteta could minimize the risk of injury to his players by focusing on just two competitions.
Arsenal are now focusing on the Premier League after winning 5 points from Manchester City, Arsenal chances are very open to maintain their position until the end of the season. Arteta can rotate when his team has the upper hand against weak teams, he can withdraw the main players to give him more hours of rest and keep his condition fit so that he is better prepared when playing in big matches.
regarding the FA cup, yes, I think arsenal only fielded the squad or the second team, considering that they still have many matches in other leagues and maybe arsenal is no longer curious about the FA cup, which has even won trophies 14 times.
Yes, I agree with you regarding Arsenal being able to focus on the English league, one of which is, considering that this Arsenal club is playing not only in 1 league, it can make the core player risk even heavier and require Arteta to think about a strategy to arrange the players in optimal and prime condition