I think this is a key issue.
In many word processors creating a headline requires invoking a program function. In markdown, it is simply a text expansion (or conversion).
Wysiwyg markdown editors, and a few others, have put in buttons and shortcuts for them - but what is written in the document is still a simple text expansion.
For h1-h3, typing the required number of #s is quicker than most “shortcuts”, but obviously not when you reach h6 and have to count precisely. But it is still just a test expansion.
Personally, I’d prefer to save official Obsidian shortcuts for Obsidian commands rather than text expansion.
Obviously, I do use a text expander, which has the advantage of working in all programs, because I agree that counting h6 is an unnecessary pain.