My Original comment here (too late to delete):
Beware. When you reach the end there is a "more projects" button. In there is a cute IQ test (possibly appealing to the HN crowd). When you reach the end of the test it asks for email, and then ultimately wants $1 to get your results. If you pay by credit card due note that there is an auto-checked box for some $29.99 per month subscription for... something.
The use case is mainly driven by htmx where you will have lots of these partials and the view code renders them as individual responses.
Also, serious question: Are they any GUI toolkits that do not use multiple inheritance? Even Java Swing uses multiple inheritance through interfaces. (I guess DotNet does something similar.) Qt has it all over the place.