Suspicious part suppliers (Worldway Electronics, Utmel Electronic, Robosynatics, etc...), what are they about?

I'm currently looking for some FLASHPRO4 peripherals, which are naturally hard to find as they are old devices, and the reputable dealers like Digi-Key, Mouser, and Newark all have none in stock. If I go to a site like Octopart, there are multiple sites listed that claim to have thousands in stock, but they require that I input a bunch of my personal information just to get an RFQ. It feel suspicious to me, why can't I just buy the part like on Mouser? Why do they need my personal information before I can even attempt to buy the part? Is it just a ploy to get my personal information? If anyone has any personal experience or knowledge about these oddball electronics dealers, I'd love to hear about it. Are they legit? Or do you put in your personal information only to find out that the part isn't really in stock? All input is appreciated.
I have not personally dealt with these for my hobby projects, but I work for a power electronics manufacturer, and recently, a project I am on needed to acquire some parts that are no longer in production (and in particular, not by the original manufacturer). We needed to acquire a small quantity of the part for testing since it had been qualified in our BOM system, and someone was concerned that a constract assembly outfit may have used them in the distant past since they had been qualified.

These secondary distributor outfits either directly stockpile old inventory, or they act as agents to acquire them from companies that do (that's why not infrequently you may see more than one outfit that seems to have precisely the same quantity as quoted by another). The ones acting as agents will need to perform a transaction to acquire the parts to sell you (and will be doing so as a mark-up) and need to ensure there's a deal before they purchase the stock for re-sale, because it isn't simply sitting in their own warehouse.

As a rule, many of them will be selling NOS (New, Old Stock) at a premium, and may have MOQ that are on the order of full reels, rather than a dozen pieces, and if you do arrange to get a handful of pieces, they are likely to be marked up significantly, since they've no idea if they will ever be able sell the rest of the stock they may have had to get a whole reel of.

If you're finding them shown in the output of a search on Octopart, by and large I'd expect they're not totally fly-by-night.
Thanks for that info. I've read elsewhere that some of the secondary distributors do some bait-and-switch tactics, and I think we've all seen articles about counterfeit ICs out there, so it feels risky trying to procure parts from sources I'm unfamiliar with. Anyway, thanks again for that input.
Though, I just performed a search on Octopart for LM311, and there are a lot more alternate sources than I've seen before, so Octopart has extended their list of alternate suppliers.

search for TPS62160 (a TI switchmode), and the extended list contains 20+ vendors, which is more than it used to be, so the "of it is listed with Octopart it probably isn't fly-by-night" may not apply. One is:

They're in South Africa, and the pricing on that page basically matches what Octopart showed (25 per unit) - I homed in on that one because I wanted to know why it was so much higher than the others. There isn't a currency listed on the website - SA uses the rand as currency, which is about US$0.05 - which brings the part price more or less in line with many of the other vendors, versus 20X as much.

So, it seems the pricing in Octopart may not account for currency type, or lacking one, assumes USD.
Thank you, splud. Yeah, I'm not about to start ordering parts from any and all vendors listed on Octopart, but I might start making low-risk purchases and keeping track of which vendors send bad products. It would be nice if a website like Octopart did most of the legwork to vet the vendors on their site, like maybe allowing customers to report back and/or rate the vendors based on their experiences buying from them. Vendors who sell counterfeit parts or use predatory pricing tactics could get "downvoted" into obscurity, while reputable vendors rise to the top. If I had the means, I'd make such a website myself.