Surely, I don't jest. Although I did say what type of spray lube you care to use doesn't matter, it has been corrupted to mean WD-40, which I specifically did not single out.
OK, I shall say this again. This is a quick and easy way to do it. Am I saying it is the correct way? Nope, and I even stated that, IF you are in a hurry, IF you just want to do a quickie or IF you don't want to follow the manuals instructions, by oiling the machine in this way, at least you get some oil where it is needed. Regardless of what anyone believes, just by doing this, as messy as it may be, you will extend the life of the machine.
Now then, I did not say this was proper, that this was legitimate nor did I say it was recommended by a manufacturer. However, oiling it this way is the least, read that again, the LEAST someone can do to keep their machine up and running. Had my own mother, and countless other people who brought me their own ruined machines because they never oiled them, just done this very simple way to get some oil on moving parts, those older retro machines may still have been sewing to this day instead of ending up in the salvage/recycling yard.
Now then, would I ever use this method? Absolutely not. I clean them and use military spec bearing lube. But there are many, many people who have these machines and they refuse to oil them at all. (Some older Necchi's have 30-something oiling points, and even though I repair machines for a living, these are even a pain in the tail for ME! Imagine someone who has zero mechanical ability and is faced with the prospect of getting oil on all of those joints. It doesn't happen, and I have revived many a dead Necchi because it was never oiled.) In that case, using a spray lube on the machine, as I have described, will at least save it and keep it usable.
So please everyone, let's not in any way say that this is the end all for lubricating sewing machines. It is a quick way to get oil into the moving parts with not a lot of hassle. In reality, the machine should be properly lubed by someone who knows sewing machines and can take the time to do it right. BUT, if that isn't an option, you can spray lube the entire mechanism, and the machine will keep functioning. No more, no less.