Some anime arcs get more credit than they deserve. Overrated anime arcs aren't always terrible, sometimes they simply aren't the best the show has to offer. This can be said of the Provisional Hero License Arc in My Hero Academia. - while there's little inherently wrong with it, it doesn't rank among the best because the stakes are far lower than the rest of the series. At other times, the arc is actually a disaster - the Pharaoh's Memories arc in Yu-Gi-Oh! is an excruciating tangle of nonsense that sells its fascinating content short with bad pacing, continuity failures, and uneven art.
Which anime arc is truly the most overrated? That's up to you.
The penultimate arc of a long-running series should aim to be one of the most emotionally resonant segments, but the Pharaoh's Memories arc is a disjointed mess. While it's great to learn about the Egyptian backstory, it doesn't make up for all the other problems that riddled the arc. The pacing is terrible, and it makes it impossible to keep track with the plot. The ultimate villain, Zorc, is more laughable than threatening, and is far less memorable than earlier villains like Pegasus. The arc also demonstrates the show's failure to incorporate its filler arcs into the rest of the series - Yami Yugi undergoes a lot of character development during the DOMA arc that's completely reversed here.
Yu-Gi-Oh! has been hit or miss from the start - some episodes are amazing, while others are total nonsense. It's not surprising that the end is a disaster, but it is disappointing.
Attack on Titan is arguably an overrated series as a whole, but one arc stands out as being more overrated than others. The Female Titan arc, which closed out the first season, was somewhat intriguing because it introduced the idea that Titans could be intelligent. The problem was that it ended on a cliffhanger - viewers find out that Annie was the Titan, but there's no indication whatsoever as to what her motivation was - only a series of vague flashbacks to her childhood that provided few, if any, comprehensible clues. Cliffhangers work when you have a hint or two to consider while you're waiting for the next part, something this arc failed to provide.
For many people, the beginning of Sword Art Online is the best part - and compared to any scene where Asuna is in a cage with Nobuyuki Sugou, it's pretty great. But on its own, it falls a little flat. While it's effective at establishing the world of the MMORPG the characters are trapped in, it doesn't do a great job of establishing an interesting protagonist.
The focus on Kirito being a beta tester takes up way too much space for a detail that doesn't end up being terribly important later on, and it can sometimes feel like a stand-in for a personality. Also, watching him repeatedly prove how much better he is at gaming than the various female players he encounters is predictable at best, and mildly sexist at worst. Kirito will ultimately experience more character development, especially during the first arc of Sword Art Online II, but the Aincrad arc is part of why some viewers write him off as featureless.
The Dressrosa arc is often hyped up as one of the best arcs in all of One Piece, but is the hype justified? Probably not.
The first problem is that the arc introduces way too many characters, and then fails to spend enough time on any of them to make them memorable. It also fails to take advantage of its magical setting, putting all of its energy into a never-ending parade of new characters who won't ultimately add to the overall story. The arc features a deep dive into Donquixote Doflamingo's backstory, but in the process of revealing his backstory, the mannerisms and obsessions that made him such a striking character to start with fade into the background.