Well that was a choice they made themselves, Barry went back without telling anyone.
I think Barry deserves the power of doing shit on his own from time to time but Flashpoint and the effects thereafter, are all about selfishness from all sides. There was no way that anything could have remained as hopeful and gleeful (lul glee) as they were pre-flashpoint. It was either we get super emotionally rekt Barry for half a season or emotionally rekt supporting characters. It turns out we got a bit of both. But, like they've said and you pointed out, Barry did Flashpoint without telling anybody else and that's the big issue everybody has.
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Maybe if we got a emotionally rekt Barry, we could have gotten a Flash that just went on a killing spree and said to himself, "no more. Every villain I've encountered has destroyed my life and many others. It's time I take your life away. No more nice Flash." A Barry that taps into his Speed Force and kills with no remorse would have been interesting to dive into.
Flash is emotionally rekt, drinking heavily, and just not giving any fucks. Just imagine a morals off and bloodlusted Barry Allen for half a season. That would be entertaining but then we'd all be screaming, "throw in the damn towel! They're all dead! Stop it Barry!!"
A rogue, morals off, and bloodlusted but in control Barry Allen would be interesting for a season imo. People will just remember a streak and the evil meta's with a hole in their chest. STAR Labs trying to find Barry and bring him back and question him why he is doing what he is doing. Just a Barry Allen disconnected from his Earth. They can't find Barry because Barry is on a barren Earth(s). Barry nearly masters the Speed Force and he is literally too fast that all people see are his streaks. STAR Labs, in a desperate move, calls for Jay Garrick's help. Then we would get a crazy Speed Force battle between Barry and Jay. Jay destroys Barry, tells him and convinces him that things can and will get better. Barry, an emotional wreck, returns to Earth-Prime, turns himself in for the deaths of hundreds of metahumans, and that's how we get locked up Barry.