"Like", but not entirely accurate.
There is no doubt that many of the Chinese suppliers are simply what in China are called "Trading Companies" that are buying the finished product from the producer and selling it as their own. Some have their own fulfillment operations in China, but also may use the same transportation and logistics providers as others; and some are definitely just following a drop-ship model.
There are however companies that are actually producing the finished products, but again may use the same transportation and logistics providers as the trading companies.
Basically, it comes down to five levels of "supplier":
1. The actual manufacturers synthesizing the raws (there are estimated to only be 3-5 such companies doing this for the specific products we're buying)
2. The producers or "fill and finish" companies who actually take the raws, process them, dispense into vials and then lyophilize (people I trust suggest there are perhaps about two dozen of these companies)
3. Trading companies that custom order their products from #2 (dozens of companies)
4. Trading companies that simply re-sell products from #2 and may or may not have in-house shipping (hundreds of companies)
5. Domestic vendors who purchase their products from #'s 2, 3 or 4 and resell at retail
Some companies may be a combination of #2 and #3, and that is what QSC, Senwayer, and (formerly) XCE/CA are generally believed to be doing. I won't get too deep into the "sausage making" but suffice it to say that the suppliers who are able to provide custom production runs on demand are pretty much all in this group.
One of the biggest frustrations I experience in the research peptide hobby is all of the "Has anybody bought from XYZ?" questions people constantly ask. They've spent some time on Made in China, Global Sources, ECHEMI, etc. finding suppliers, contacted them and gotten what they think are great prices and of course a rep calling them "honey" and "dear" and telling them how well-reviewed their products are and how they'll love them long time. Then they start to think they've struck gold and found the next best supplier and are eager to share with the world or at least get reassurance that they're not buying bunk because of they're usually not willing to pay for their own testing. Those kind of people are how all these suppliers have proliferated; it's an endless supply of people shopping for the lowest price above all else. The best price doesn't necessarily mean the best deal.
