Arsenal had finished 5th with 70 points the season before Arteta took over. Emery got off to a bad to the next season and left them 4 points behind 5th, and 7 points behind 4th in December when Arteta took over. When Arteta took over the points gap between themselves and 4th/5th increased. Now I'd give him a pass for this part-season, but revisiting this season is important for context. It's bordering on impossible not to improve them in subsequent seasons from this position, which was 8th place with 56 points. They had gone from the 5th best side and underperformed hugely on their way to a midtable finish, no one would expect them to remain midtable
Arteta's 1st full season he managed to improve them by 5 points, and finish 8th again, I find it absurd that this is somehow a clear sign of a great manager building something great. All we knew at the time was Arsenal had a laughably shit season under a manager who had no proven record as a manager prior. Getting excited for this "improvement" would be like United fans getting excited if ETH gets us a 5 points improvement on last season's calamity of a season. It's a rival forum and Arsenal had just had consecutive 8th placed finishes, you'll have to forgive the Caf for not heaping praise on Arteta for such monumental progression.
From there Arteta spent £150m in the summer for a further 8 point increase on his way to a 5th placed finish on 69 points. So, after 2 and a half years he managed to finish on less points than Emery managed in his only full season, and still has no top 4 finish to show for it. Maybe what they lack in substance they made up for in style with great attacking play? Nope, 5th highest xG in the league and a tendency to park the bus whenever they go a goal up.
It was all progression from a very low starting point. If a person's view was "listen, it's all a bit shit to watch but we're slowly improving and I'm willing to continue the slow progression for as long as it lasts, if we ever stop progressing then we'll have to pull the plug", fair enough. But let's not pretend there's anything weird about rival fans having a chuckle at a manager finishing 8th twice.
I like Arteta unlike many on the forum but I think that first two years at Arsenal was nowhere near the narrative you have described. Incremental improvements in performances is correct but if Arteta had the same trajectory at any top four club not just in England but Europe he would have been sacked without hesitation of it even being considered a questionable decision.
Arteta has benefited from two things the which are a young squad where the expectations have been fairly minimal and a very transparent board member in Kronkes son who has had patience in the transition. This is a situation where Arteta owes Arsenal more so than the club owing him.
I'm not saying rival fans were wrong to look at results and draw their conclusions. Of course thats what they are going to do. However, the best judge of how the club is doing is their own support, which takes into account many things including results, performances, connection with the players, connection with the management, connection with the board and owners, atmosphere in the ground etc. In nearly every aspect of this Arsenal were getting towards lows not seen in years, decades perhaps.
Season tickets were still being sold as people didn't want to give them up, but there started to be more and more empty seats as fans simply couldn't be bothered turning up half the time. The fact the seats were sold but punters still didn't want to turn up told you everything you needed to know.
Now I totally agree it's not been a linear improvement on the pitch. There was initial highs of FA Cup wins, and there were real lows like the start of the 20/21 season, where every Arsenal fan admits he could easily have been sacked. However, he turned it around that Xmas and since then I think most fans started to wake up to what he was trying to do, could start to see an identity, and could start to feel a connection with the team. The positivity on the park and from the stands started to feed each other.
Even then it's not been perfect, it's not been plain sailing, but it was never going to be. At times it's been 2 steps forward, 1 back, and yeah, it's required patience from the fanbase and owners, but hopefully that patience is paying off now. Who knows, with Man City and the rest of the competition in the league it might not lead to any rewards in terms of pots of gold, but at the very least hes helped make the fans actually enjoy their football again however temporary it might be, and at the end of the day, with limited trophies available, thats the main thing.