I think we can disregard that KB article, because, as you say, it's about FAT32, which neither Google Drive nor Dropbox use, and it doesn't give any details as to why FAT32 drives are problematic
Perhaps you need to re-read my last paragraph:
...but check the forum here or over on Aperture (which uses the exact same Library) and you'll see the many reports of folks whose Libraries have been trashed when stored on a NAS or Server or inappropriately formatted disk.
So, no, I don't think we can disregard that article. As to why? Well the common mistake is to assume that the iPhoto Library is just a bunch of files. It's not. It, the Aperture Library and libraries from 3rd party apps like DevonThink and even Lightroom are complex ecosystems of interlocking SQL databases, XML and impeta files that manage the interrelationships between the Masters, the Previews, the Thumbnails and so on. (and btw, knowledge base articles rarely explain why...)
And while you're copying a folder to the cloud, what is the folder sitting on when it's in the Cloud? It's not about the device, it's about the disk format the Library is sitting on. So, find a NAS or Server formatted Mac OS Extended (Journaled) and you'll have no problems. But if it's sitting on something else then the risk of corruption is very real indeed, especially once you start to write to the Library when updating the back up.
The problem referred to in the first two articles - about the symlinks - arises in one specific case only: Libraries updated from an earlier version to iPhoto 11. It does not exist in newly created Libraries at all. But these articles say nothing about the data corruption issues that are caused by having the Library on an inappropriately formatted disk - issues from problems importing, exporting, saving edits and sharing the photos up to lost metadata, lost edits and so on.
No disrespect to the folks you linked to but you have to read carefully and cautiously. Both of those articles are more than 15 months old and there have been a lot of updates since. Are you sure they're still current? On the google link some of those pages are more than 2 years old, predate iPhoto 11, predate the common iPhoto/Aperture Library. And they make common mistakes like: :
The photos you have edited are saved to a different folder inside your library, named Modified. Guess what? This folder was also renamed and symlinked in iPhoto '11, now it's called Previews. And there goes another duplicates to the Dropbox server…
No they are not "the photos I have edited". That's not what Previews are. They have no role in editing at all. It's all virtual in iPhoto 11. The previews are there just for media browser access. (You can actually not use them at all - there's a setting to turn them off in Aperture.) And, no they're not duplicatesl... The point is if the person is unclear on what the elements of the Library are, what their role is and so on, are you sure that's the plan to follow?
My aim in writing is to let you know what I have seen and learned on here - and not only you. This is an open forum and lots of people search the site and never post. The desire for a cloud back up of the Library is great. It comes up here quite a lot. But, as of this writing the fact remains: there is (unfortunately) no reliable cloud back up for the iPhoto Library.
By all means experiment, but I would not be using it as your sole back up.