There is logic and reason to that, and I don't see a problem.
There are two kinds of people who are making these groups: The people who are experienced and want a quick clear on their alts with other people who are experienced and want to clear it quickly.
Or the people wanting to be carried.
Both groups are entitled to take whoever they want into their group. It does suck when you can't get a group for a Normal mode raid because you haven't done Heroic, but there's literally nothing you can do to prevent that from being a problem.
People are always going to check gear, logs, and achievements when it comes to forming their own group. That's why the best way to play WoW has and probably always will be with a guild full of like-minded individuals. That way you can progress through Normal mode raids super casually together at your own pace.
And I'm not using that phrase as a derogative. If that's the way you play the game, then you need to find a group of like-minded people to play the game the same way. It's just the best way to do it.
Any time you pug anything you're not going to be treated fairly.
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I'm not sure of the specifics, but I can only assume it's related to the consistent updates to the game that have made it more and more casual?
Like... LFD and LFR have gotten people to decide that they didn't want to join guilds, but then they run into this issue where they aren't getting invited to content because they don't have a group of like-minded players to enjoy the game with together.
The game used to be centered around the mentality of "If you aren't in a guild, you aren't going to do end game content" to "It's fine to be guildless, we, as developers, will do everything that we can to make sure that you are able to have fun" when the second mentality just really doesn't work.
So, instead of those people quitting the game or finding a guild, they whine about it to Blizzard hoping that things will get changed somehow. Ultimately, I don't think anything Blizzard could or would implement in the game would fix the issue of needing a guild or a friend group to have a good time playing the end game content.