First, here are the sources:

0 The blog post which references the survey.

1 Admin stating that "about 21 million saw the invite [to take the survey.]"

2 The survey brief mentioning "you gave us 16,817 responses."

3 The survey admin clarifying he truly has no understanding of selection bias. When somebody else brought this up he stated, "We were pretty careful about showing the survey invite in a randomized way. This is pretty standard survey methodology - taking a randomized, representative subset."

4 The "scrubbed" survey data in CSV for anybody that'd like to look at it.

Citing #1 and #2, 99.92% of people chose to not participate in this survey. For anybody here that might not be familiar with selection bias, it's the reason internet sourced anonymous surveys are simply (and literally) not used when seeking actionable data. People who opt-in to surveys without other sorts of incentivization (which itself can also introduce bias depending on which people are attracted to said incentives) disproportionately represent those who are driven to do so for reasons that are generally not representative of the userbase as a whole. For instance upset or unusually enthusiastic users are going to be more likely than not to take surveys on the quality of a site. Randomizing who sees the survey does absolutely nothing to deal with this when only a biased sample opts in to taking it.

Now for the more interesting stuff.

The above all shows a lack of technical competence, but it's nothing particularly surprising and I think we can safely invoke Hanlon's Razor. However, now we're about to enter into the realm of mental gymnastics used by people trying to validate something that is clearly unpopular.

"50% of people who wouldn’t recommend reddit cited hateful or offensive content and community as the reason why."

"3.25% of respondents cited hateful or offensive content as a reason they would not recommend Reddit."

The first is Reddit's phrasing, the second is the in context figure from the data itself. 93.5% of respondents actually would recommend Reddit. They take the view of a minuscule minority (which works out to 543 users in this case) and rephrase to make it seem vastly larger than it is. But this gets much more interesting very fast.

The words "hate" and "offensive" (or any variations of such) don't even show up on the survey.

The only way people could mention this would be in the free form response category. Unfortunately those responses have all been deleted from the public data, citing privacy concerns so it's absolutely impossible to verify or determine exactly how they're coming up with this figure. We do know that, citing their own report, there were only 111 responses to why people were extremely dissatisfied. So we're left to assume that the vast majority of these responses from people who would not recommend the site and find the content "hateful or offensive" actually aren't extremely dissatisfied with the site........

I'll sum up with quoting the Reddit admins' interpretation of these data that was shared on the blog post

TL;DR: We are unhappy with harassing behavior on reddit; we have survey data that show our users are, too. So we’ve improved our practices to better curb harassment of individuals on reddit.

Lies, damned lies, and statistics.