What were some of the biggest mistakes that Yahoo made with the running of this Answers site?

I totally agree with you, especially your first sentence. I would add 'lousy programming' to that list. Verizon Media should have either gotten rid of the Answers portion when they first bought Yahoo, or they should have made their mind up to turn it into a decent website. They did neither.  Had they chosen the route of making it a decent and respectable website, Advertisers would be attracted to this place, and Yahoo would have made some money. As it is, advertisers have deserted Yahoo, and all this site does is make Verizon media look bad.

No good business makes themselves totally unavailable to the  users. There was literally no way to contact them!!! I got particularly frustrated one day, and called the number on the be bea bee site (see how I had to spell it so my answer would not be hidden?) I give you my honest word that I got a medical device company. So I contacted Be Bee Bea, and told them about it. The next day the number was gone, replaced by  help etc. No way to contact them and actually get help, unless you want to pay for tech support, and that is only tech support help, nothing else.

Actually I agree with all the posts I see so far!

- not doing maintenance

- allowing way too many answers and questions to be posted per account

- ignoring pleas of users

- disbanding the answers-team

- allowing blocks on anonymous questions

- malfunctioning archive, so many questions were asked over and over and over

- allowing "best answer" to be chosen after just one hour

- having a "polls&surveys" category

- Difficult to view oldest questions

- Difficult to view questions that I have not picked a best answer for

- Can no longer view my best answers

Slow to fix glitches,  or never fixed them at all. 

Green to Purple format.----you can only HOPE that idiot was fired. 

Giving level 7 TROLLS   question moving abilities........stupid.  Very Stupid- 

Taking away emails-----

and of course,  giving TROLLS the power of Anonymous. 

The pathetic half assed attempts at moderation......

allowing trolls to falsely report anything they want........without reason. 

Need I go on? 

Some were:

Not fixing the technical issues that were allowed to continue for years

Turning off content removal notification so users would have a hard time appealing wrongfully removed posts

Disbanding the YA Team we had for a few months in 2018 (which allowed us direct contact with a YA Team member, for serious issues)

No oversight of YA which allowed trolls/abuses to flourish and other users to become apathetic to reporting the violations they saw

Randomly locking people out of their accounts and taking down questions that did not violate TOS

The Trusted Reporters were not the problem (I actually was one for several years, with the power to remove a question or answer based on my sole report).  The problem was the Trusted Reporters who became self-appointed Hall Monitors, over-zealously policing the site for anything they deemed an infraction even when it was clearly not.  They became most active in the period circa 2012 to 2013, and drove away a huge number of good users, creating a vacuum that was filled by trolls.  And that was the snowball that started rolling down the hill.

However, official site moderation was impractical.  At its peak, questions were rolling in by the second, receiving 5 to 15 answers, plus comments, plus feedback on Best Answers...it would have cost millions to have paid moderators.  A simple control on the Hall Monitors would have been more effective.  They were also Point Accumulators so I advocated that every over-turned report would cost them 5,000 points.  When they'd lost 50,000 points, they'd lose their Trusted User status.  THAT would have made them a bit leery about reporting some harmless chat or a simple "No" answer to a Yes or No question.

If not controlling the Hall Monitors was a big mistake, another one was the 2014 Green-to-Purple format change, and all the other changes that went with it.  It was widely despised but Yahoo would not, or could not, undo it.  And that's when the snowball really started to pick up speed and volume.

Finally, in the period 2015 to 2016 or so, the site was basically left hacked open for months at a time, for all sorts of odious content that no amount of reporting would remove.  I had been a regular user since 2008 but that's when I switched to a very occasional participant.  You could feel the end was coming, but I am a bit surprised it took 5 years to get here.  It's almost like Verizon forget this was even part of the purchase.

I agree. Lack of proper moderation has  been a huge problem. There are lots of obscene and insulting posts on here, but at the same time my answers have been removed many times just for agreeing with a question, stating simple facts and even quoting from the Bible. 

Some of the rules are petty and silly. I lost appeals because the rules state that you cannot include a question in your answer, and you cannot agree with just the word yes. 

Common sense all around would have been nice. Fun is always good too. 

not letting my points be turned in for cash prizes didnt help much either