There is a difference though. Arteta and Howard's comments talk about adding to the squad, signing better quality players. Neither of them talk about how that comes about, because it's not their place to comment.
Phil Neville actually said something along similar lines:
"I think it's something you need to do, you need to keep adding to the squad. We have done that every season since I have been at the club. It provides competition for the players and keeps the players motivated.
"As players all you need to do is look after yourself because we have faith and trust in the manager and chairman to provide what the team needs."
This is fine. There's nothing wrong with a player of a club saying that it'd be good if they can have better players to play with.
But then you get things like this:
“It is the way of the world at a club like Everton,” said Neville. “Sometimes to move forward, you might have to sell one of your better players, like we did with Rooney.
“But the year after we sold Rooney, we qualified for the Champions League, so it isn’t necessarily a bad thing sometimes.
“Sometimes you just have to take a hit on one of your superstars, and take one step back so you can take two forwards.”
He's trying to give his opinion as an outsider looking in, but also as a player at the club, so he's tripping himself up. Things like, "It is the way of the world at a club like Everton" and “Sometimes you just have to take a hit on one of your superstars, and take one step back so you can take two forwards” - that's the kind of thing you'd hear an unemployed manager say. Yet then at the same time he's talking about how 'we' sold Rooney, even though he wasn't at the club when that happened.
He needs to make his mind up about what position he's speaking from.