To be clear, I'm not trying to argue with you on your points. I'm just digging for my own knowledge using your points to google with, trying to understand the need here.
I've been here a long time, cPanel does not ignore anything. cPanel doesn't do what other control panels do though, and that's why it's the hosting platform of choice!
To be fair, I am talking about our large client base which is primarily developers that work with specialized applications. From what we gather they are using Full JSON support, which is now included in MariaDB 10.2, but many are also using MySQL X Plugin which gives them the ability to mix a scheme and schema free database design. This gives them flexibility in design and the ability to take advantage the schema free features where needed in their code. The other feature we are starting to see requested is in delayed replication, but that presently is not really a client that would use cPanel.
Now our developers have also always been on the cutting edge, but we see what they do slowly become standards in the industry. For example we saw larvel adaptation long before it became main stream by many paid applications / scripts.
The other part of our client base is clients that use mainly commercial scripts as most of them are well established businesses and need the support of their software vendor when they encounter an issue. So as these commercial scripts are stating that they will work with MariaDB, but there will be no support if an issue comes up is highly concerning.
Also to be fair, the majority of dedicated clients do not use any control panel, but the fact that we havent sold a cPanel license in months to a dedicated client and clients are either going with DirectAdmin or bringing their own Plesk license with MySQL 5.7 being one of the main reasons is also what is raising huge red flags for us.
When I talk about what other control panels are doing I am talking about core support of main software all because cPanel decide for the community to bail on a industry standard because they felt MariaDB was better. And is come configurations it is, but in others MySQL 5.7 can be faster depending on the configuration. This the ridiculous part to me, especially when its been clearly documented that the only reason it will not work is due to way the user.password column works in 5.7.
Now if I was complaining because Litespeed decided to change their apache format configuration and the version was broke in cPanel, I would understand not rushing to support it.
But just for fun, lets look at the top 10 control panels (paid and not paid / in no particular order) used by the hosting industry today
cPanel - MySQL 5.7 Not Supported
Plesk Oynx - MySQL 5.7 Supported (Hack for MySQL 8.x)
DirectAdmin - MySQL 5.7 Supported
Centos Web Panel - MySQL 5.7 Supported
ISP Config - MySQL 5.7 Supported
InterWorx - MySQL 5.7 Supported
Webmin - MySQL 5.7 Supported
ISP Manager - MySQL 5.7 Supported
Vestacp - MySQL 5.7 Supported
Kloxo-MR - MySQL 5.7 Supported
All have had support since sometime in 2016, so at least 6+ Months. The fact that cPanel does not understand this is an issues is why I am amazed.