I followed him fairly well, I think.
The endless chain is only made endless by use of a master link.
Sorry if I came of sounding harsh. (shrug)
My main point is that the bike mfg probably cuts the chain, supplied by the chain mfg, to the length needed for each bike. One may need 104 links, another model may need 112 links.
And they may well be put together prior to being put on the bike. But no matter when the chain is assembled, it has to be fastened end-to-end by a master link...of some sort.
The factory may well have some tooling set up to press on the attachments, inject grease (if need be), and stake the pins all in one shot. Where as you have to do these items individually, and with hand tools.
Other bikes will have chains with a clip type master link. Those are assembled by hand, in the factory or in the garage.
The guy installing the chain on the bike in the factory (which he probably isn't doing anyway..probably the dealer) may well think that the chain came from the chain mfg already to go as he needed it, but the chain was put together somwhere upstream in the assembly process by the bike mfg.
The guy who puts the bikes together at the dealer may also think the chain was done at the chain mfg like that, but it was not.
Many who have endless chains, (which btw is actually a chain full of identical rivet type master links), will opt to use a chain breaker instead of taking the rear wheel and swingarm assembly off to get the chain removed for cleaning.
Using the chain breaker allows you to inspect the internal condition of the links friction points.
On a sealed ring chain, this also will give you a chance to inspect how the lubricant between the sealing rings look. If it looks as if the grease is depleated, you can bet the rest of the links look the same.
If you use a lube that doesn't make cleaning hard, and keep an eye on your chain by adjusting and measuring occasionally, you shouldn't have to take the chain off until replacement time.
Of course having the proper replacement master link, and the proper tools for the job is very important.