Yeah, it seems like this is a thing.
I think that most young folks will not understand why Huawei/Honor is doing this and I can't say for sure either but, I have a few thoughts about this that I thought I'd share. First companies don't do things like this for personal reasons. Companies, make decisions based on the numbers ($) and what they view as "the best interests of the company". So, my first thought is that, the increase in the amount of money being spent in support for n00bs bricking their phones flashing ROMs and possibly, the money spent in maintaining the process of allowing bootloader unlocking is growing to high. This would include, but is not limited to, all things involved in "shipping your phone to a service center". From paying "technicians", shipping, logistics of maintaining services centers and complying with local laws all across the world which I am sure vary wildly. I am betting they "worked the numbers" and found that the bulk of support costs were the result of ROM flashing. Cost/Benefit Ratio...
Some of you might not be aware of this but Huawei/Honor has trouble in USA markets because of tensions between the U.S Government and China. Earlier this year AT&T dropped a huge deal with Huawei under pressure from the U.S. Government. You can read about that here. I do not know what effect this tension has done to Huawei/Honor's business. Perhaps this plays a role in their decision? Just a thought.
Huawei/Honor seems like it can't make up it's mind. It starts and "Honor Open Source Program" which would seem to suggest a commitment to Open Source and then in direct contradiction chooses to end a service that would be required for this program to spread to other devices, guaranteeing that the program does not grow beyond this one device. It's like the old saying about the left hand not knowing what the right hand is doing.
I am sure that Huawei is doing what it thinks is best for itself. Nothing wrong with that but as a consequence, I think the development community will surely dry up which means I should find something else to do ;)