Nope. You didn't read the article. The peptide hormones usually don't even occur in "a healthy diet" or at least a common one, nor would they survive a digestive tract. They are chains of a few aminoacids, essentially very very short proteins. Insulin falls under this category. Yes, they have to be kept relatively cool and have to be injected, most or all of them.

And they are genuinely useful (not just the insulin). Semaglutid for example was first isolated from some reptile's salivary gland (healthy diet??) and is very effective at controlling diabetes and regulating appetite in people who have an obvious issue with that.