The CB1 cannabinoid receptor, the main molecular target of endocannabinoids and cannabis active components, isthe most abundant G protein-coupled receptor in the mammalian brain.

https://pubmed.ncbi.nlm.nih.gov/24843137/

Is it a big surprise that ingesting cannabinoids will fill up cannabinoid receptors, preventing other nasties from binding?

Side note- nicotinic receptors are also very prevalent. Why do you think they have a war on tobacco?