I think the parent commenter might have an aversion to people ubiquitously storing their ideas on a closed source platform rather than rolling their own.
I agree with you, but its more about the message you send when you reinforce and inadvertedly support a certain way of doing things or sharing information. Some would prefer it was 100% open down to the backend.
I think the obvious issue with that line of thinking is “where does it end?” Do you have to own the hardware, or can you rent it? Does the hardware design have to be open? What about the network? Do you have to own and design that too? Presumably the idea is “as much as possible should be open”, but of course what is possible varies from person to person, and for many of us, a GitHub CDN is the boundary of “what is possible” largely because it is dramatically easier than alrternatives. So I don’t see any coherent argument in favor of the OP’s position.
This is the only interpretation I can somewhat support. However, this applies to most blogging platforms, and therefore still seems questionable to me.