The fact is that a shocking number of agent websites are awful. These are legitimate agents. Some of them have surprising numbers of best-sellers behind their names. Their websites still suck.
Why?
Because they're agents, not programmers. They don't have the time or the inclination to do this kind of thing, and frankly the incentives don't require them to get better.
While we're here, let me also point out that there are no qualifications and no certification associated with being an agent. None whatsoever. Any of us here could put up a website and start taking submissions. That doesn't mean we'd be good at it, but the line between "agent" and "not agent" is shockingly thin.
Don't believe me? Here's an alphabetically sorted list of (probably? mostly?) real agents. You can go check out their websites yourself:
https://www.manuscriptwishlist.com/find-agentseditors/agent-...
I was upset enough about this situation at one point that I wrote a whole essay about it, along with a website template to show them how to do better. But then I thought better of it and decided it would be better not to burn my reputation in the industry, even if their web design skills leave me wanting to put my eyes out.
Bottom line: I absolutely agree that an agent should never cold email you (unless you are already very successful, in which case hopefully you have better sources of advice than an HN thread). They should absolutely never charge you money. And you should be very careful with referrals they give you if you're not very confident they're legit (or frankly, even if they are).
But if their websites suck: well, sorry, that's sort of how the industry goes. (Unless you never want to work with a boutique agent, ever.)