The 21-year-old has not been given a single opportunity in the first team since his £27m from Saint-Etienne in 2019 and has been shipped out on loan three times back to France already.
Saliba impressed at Nice during the second half of the 2020-21 season, leading to suggestions that he would be integrated into the first team of the summer of that year.
Saliba made 51 appearances for Les Olympiens in all competitions as they secured a second-placed finish in Ligue 1, while also winning the Young Player of the Year and making the Team of the Year.
Following Marseille's return to the Champions League, Saliba stated that he would be keen to experience top-level European football with Les Olympiens next term.
Marseille chiefs have made no secret of their desire to sign Saliba on a permanent deal, but Arteta has effectively ended their hopes by explaining that the centre-back is ready to take the step-up at Arsenal.
Speaking to RMC Sport, the Gunners boss said: "We made the right decision. He has to come back. William wanted to be a regular starter as you know but now we want him back at Arsenal.
"He has the experience and the environment necessary to be competitive with us. If he had stayed with us this year, with a match of Premier League a week, with Ben White and Gabriel, he wouldn't have had half the playing time he had with Marseille, that's for sure.
"For his growth and what he can do next season that wouldn't have been good. William wasn't with us because he wouldn't have had the playing time to gain experience. That's it, there's nothing else."
However, Marseille head of communications Jacques Cardoze has since claimed that Saliba's heart belongs at the Orange Velodrome, telling BFM Marseille Provence: "There is a budget to stick to and a desire on the part of the owner [Frank McCourt] to make sure the club is balanced. There are priorities with regard to FFP.
"William's desire is not in doubt. He's obviously told Pablo [Longoria] and he said it to me again on the pitch on Saturday. He is sincere, but there is a contractual reality.
"He belongs to Arsenal. But if his desire is to stay with us, we will see. Everyone wants him to be here next season."
Saliba's contract at Arsenal only has two years left to run, but Marseille could be facing a two-window transfer ban after the Pape Gueye saga, with the Court of Arbitration for Sport currently handling the case.
Saliba's only appearances for Arsenal so far have come for the Under-23s, although he has been an unused substitute for the first team in cup competitions.