Ninja'ed!
This has been our experience at my table as well. And once again, IMO, the difference between actually playing it and just theorizing about it.
Table experience is really awkward as a measure because you are dealing with one set of assumptions (your game framework) that may not be even close to what other people experience. Just consider the ratio of encounters:shortrests:longrests as just one example of something that will radically change your expericne of the game and class balance.
The other bug bear is that must people don't have points of reference within their game. For example, if the discussion is, how should I build a Great weapon fighting dude, most people's tabletop game doesn't have the following sort of party composition:
A GWF Bezerker
A GWF Bear Totem dude
A GWF Fighting Vengeance Paladin
A GWF battlemaster
A GWF Champion
that would allow them to say something like 'Yup, it's all playable, but the Bezerker isn't quite as good as the totem barbarian' even within the implicit assumptions of their game!
The problem is the sort of stuff you'd see all the time in 3.5 ed when people were talking about the monk, and people who said that the monk was competitive and a very playable option in their ~level 11 game. Further digging would reveal that the GM was taking significant measures to make the monk competitive. Which is 100% OK but it means that if you're playing a monk your GM has to be OK with that and if he's not you need to be careful about what you're doing.
Gotta be cautious of that anecdotal evidence! And if you're not going to be, can you please atleast provide some relevant information like:
1) What level(s) have this game taken place at?
2) How much magical gear does the party have? How much does the Bezerker have relative to everyone else
3) How is your adventuring day working? What are those critical ratios? How many rounds are in those combats, on average?
4) What's the general party composition
5) How much healing/magical resources are spent on the Bezerker vs other party members.
6) Perhaps most importantly, what do you mean that the Bezerker is fine? I mean, it's pretty commonly accepted that the Bezerker is hella terrible, but for me terrible might mean 5% worse than an oath of vengeance based build, but for you 'hella terrible' might mean '50% worse' and thus it's really key to know what you mean when you think it's competitive.
That stuff would be hella useful to know!