So it sounds like you want to avoid passing current through the head bolts. If they (heads / bolts / block) were dissimilar metals, I would buy the argument sooner. For aluminum heads... it might be an issue in the long-term.
GM for years has grounded the battery to the block, at least on the iron-head engines I've seen. The battery charging current goes from the alternator to the head, the bolts, the block, to the battery. GM evidently is OK with this.
Most people don't have the experience or the knowledge base to know better.
Some talk without thinking.
Hence the reason for a "star" ground. Eliminate the undesired paths from being in the conducting path.
Yup. That's why one should stick with the OE ground arrangement.
A "ground plane" actually has a formal definition if you happen to look.
Pre TBI systems and their ground paths have very little in common with TBI systems.
The basic idea is that all grounds need to go to a cast iron part.
If that "path" is lost trough a bad or missing ground it will instead try to ground through a weaker or "less noble" material.
Which will be any cast aluminum or pot metal.
Which is likely sitting on a gasket.
Or only has a bond through the bolts.
Which is weak already.
The least noble material will get eaten up.
This is a known thing in the boat world and a known thing in automotive design.
And is the entire basis behind aerospace engineering.
It is an actual science
Chock full of folks folks with degrees and ****.
And that is just how metals react when differing materials are not properly isolated and grounded .
Its gets into all kinds of ionic tranfer and all kinds of crazy atoms and bonding ...