Clearly they have effects. Heck insulin is a peptide. And pretty sure it has a benefit for those with diabetes. Dismissing peptides outright is just as silly as thinking peptides are the solution to everything
You also wouldn't want to randomly inject yourself with insulin outside of medical supervision, because it can kill you pretty quick.
Injecting poorly-studied grey market peptides seems like a bad idea.
How is insulin a peptide? Insulin is a giant folded protein
"peptide" is just a category of chemical. Some of them do good things, some do bad things, some do nothing at all.
Anyone talking about "taking peptides" as a meaningful sentence is absolutely dismissible in the same way someone talking about "taking chemicals" is dismissible.