That's an absurd generalization. They contribute upstream. They aren't forking every project and keeping changes for themselves and customers. Just the sheer amount of development and testing RedHat puts into the kernel alone, funded by RHEL, should be sufficient to disprove this argument.
There's nuance here. TFA has a legit complaint that supporting RHEL puts extra hassle on you as an open source contributor.
RedHat is also fully in their right to strictly adhere to the license of the software they distribute.
Supporting RHEL as a distribution for your software means access to users on that distribution. That might mean nothing, but that depends from project to project. For the article's author that has little worth and that's a cost-benefit analysis for him. That might not be the case for other projects.
There's nuance here. TFA has a legit complaint that supporting RHEL puts extra hassle on you as an open source contributor. RedHat is also fully in their right to strictly adhere to the license of the software they distribute.
Supporting RHEL as a distribution for your software means access to users on that distribution. That might mean nothing, but that depends from project to project. For the article's author that has little worth and that's a cost-benefit analysis for him. That might not be the case for other projects.