I agree with this. Another unusual aspect of Glorantha is that people tend to pick out a god as "their guy" - at the very least, there are no codified rules effects of sacrificing to Magasta for a safe sea journey if you're not an active worshiper, while it seems downright routine to make or owe lesser sacrifices in Ancient Greece - “Crito, we owe a rooster to Asclepius. Please, don't forget to pay the debt”, as Socrates is supposed to have said, or the Icelandic A Sprengisandi folk song where the singer, feeling pursued by elves and trolls, promises a horse sacrifice if he makes it back.
The Gloranthan style of worship might come closer to mystery cults of Antiquity, though? Mithras killed a sacred bull, so by doing that yourself you emulate Mithras. In the Attis cult, we get self-mutilation as emulation. You initiate into the mysteries, and they're designed to help shape your psychology and lead to mystical insights. They're about you, not merely about keeping the gods happy.
I strongly recommend Bret Devereaux's four-parter on polytheism and how it's not even remotely like in RPGs, beginning here: https://acoup.blog/2019/10/25/collections-practical-polytheism-part-i-knowledge/