What are the reasons well established entities would post their videos on Vimeo instead of Youtube?

There is a site I have been watching - one thing i've noticed which seems a little bit out of tune to otherwise solid performance is their preference to upload all their videos to Vimeo. There is no sign of youtube embeds anywhere, on-site or otherwise.
I am just wondering what kind of benefits uploading to vimeo might get them.

Some people just need a platform to host their videos. YT being the greedy fucks they are, enforced ads on all videos even when the owner of that video doesn't want any ads on their videos.

aside from it being beginner-friendly, vimeo has quality viewers that is unlike youTube

I think you answered your question already in the way you phrased your query.

It already contained the answer.

The phrase is "well-established entities."

These are online brands.

These websites probably already have organic communities of fans and users.

If you own such a website, then putting your content on YouTube may subject you to unnecessary competition because remember, when you post a video on YouTube, once the video is over, YouTube recommends related videos.

What if those related videos are your competitors?

One of the main reasons why I see established online brands posting their videos on Vimeo instead of YouTube is that there's less chance of other competing brands poaching their traffic.

Vimeo has decent capabilities.

It is a great alternative video hosting option for established brands.

But if you are looking to build a brand or establish a strong channel, I wouldn't start with Vimeo.

Instead, I would start with YouTube because that's where the traffic is.