If you look at the names mentioned above, I personally don't agree if arsenal should sell martinelli although he didn't score many goals, but his speed and ability can often trouble the opponent's defence, so losing martinelli can be said to be a big loss especially if arsenal doesn't get a player who also has speed and ability above martinelli later, if you look at what happened to arsenal in the last several seasons, I think they need to consider bringing in two wingers to complement saka and martinelli, as well as buying one or two central striker who really has an extraordinary goal scoring instinct next season.
I also agree more with the suggestion you said because a player like Martinelli who is currently at Arsenal is an important player who must be really guarded by Arsenal, not just letting him go just because he doesn't score many goals. Because finding a player who is equal to Martinelli or even better than Martinelli will not be easy enough for any team, including Arsenal itself, so Arsenal must consider again if they want to let go of a player like Martinelli if Arsenal still wants to be a candidate for the championship next season.