Ok so you can be a really crap photographer and get a massive following on YouTube lol
Not crap but you can certainly be very mediocre.
With YouTube it actually isn't that difficult if you have the time to put in.
You don't need millions of subscribers and none of the content that is on the Sony ambassadors channels has anything to do with actual images. Actually with quite a few of them the only images you will see are from when they are testing equipment and they are often quite mediocre. It isn't a quality contest it's a popularity contest. It is the same with all of these types of programmes regardless of the manufacturer.
My eldest before she got bored with it had over 600k subscribers (non photography related) at one point and got offered all sorts of free stuff, related to the videos she was making at the time. She didn't do anything other than post a video every day. YouTube also has it's own built in S.E.O related to the tags and location information and if you know what to do and have the time to put in, it isn't that difficult to force a video to have a lot of views and become popular.
If you have the cash to burn YouTube is also one of the easiest social media platforms to fake having a following as it's super easy to buy views, comments and followers using bot accounts and not as expensive as it is to do that on other platforms. My brother works in social media and when you know what to actually look for its surprising how many of the big accounts on YouTube are buying their way to being successful on there.
He isn't a Sony ambassador but as an example Dustin Abbots photos are very mediocre and look at the large online following he has.
We don't have a huge social media following and even we have been offered free stuff and been asked to be part of ambassador programmes, not for the likes of Sony off course but for other less well known brands.
I also know someone who was once a Fuji X photographer it was a while back but it was because of the amount of traffic his blog got at the time and very little to do with his actual photography. He told me that himself.