Building a competing tool because you think you can do it better is fine. Building a competing tool because you want to take a different approach is also fine. Being rude isn't fine, and shouldn't be tolerated in any community.
If you can't take the heat, stay out of the kitchen.
Really that page is a joke and isn't very rude. It's friendly competition and clearly states why they're competing: needless complexity in the existing tool.
>Being rude isn't fine, and shouldn't be tolerated in any community.
That page isn't rude and the community will tolerate being rude if the code is any good. Look at Linus Torvalds', Theo de Raadt's, and other awesome coders' comments! They're still appreciated by the community for their code and if rudeness weren't tolerated, they'd be kicked out quick quick.
Building a competing tool because you think you can do it better is fine. Building a competing tool because you want to take a different approach is also fine. Being rude isn't fine, and shouldn't be tolerated in any community.