Can I ask why not iCloud or a Google Drive solution?
Its not so much about
not using a large Cloud option like Google Drive, iCloud, Dropbox, etc., as using different tools for different purposes. I do already use the iCloud for some things.
You raise some really, really good points that a lot more people should be aware of. I personally do use a password manager so that I can have stupidly complicated unique passwords for
everything, LOL. So I'm never all that concerned when some website I use has a data breach (which has happened to me more than once) and my login details are compromised - I can just change the password for that site and am not worried about other accounts being compromised. (I also have multiple email accounts and use some for the more "spammy", less trustworthy websites - huge help!)
I think I noted in a previous comment that I'm aware that a NAS type setup relies on the stability of your internet. Personally that's why I wouldn't use something like that as a web or mail server, even though you technically can. No way is my internet connection that reliable (we only had a technician out last week, LOL). It is unlikely going to be the end of the world if I can't access something on my NAS set up for a few days if it took that long to get an internet issue sorted and I was away. I always have a house sitter stay if I do extended travel, so I'd be aware of any internet problems as they arose. House sitter also solves some of the other issues you've mentioned.
Part of the reason I'm looking for a NAS type set up is security and privacy. There are certain documents and files that I would be very apprehensive about storing in a more widely accessible Cloud. Sure, I realise 100% that you've gotta be careful with what you store on a NAS set up too, but at least I can have some degree of control over how secure it is - that's part of the homework I'm doing now on different systems, and something that will make or break my decision to get one/a particular system. Security of the home network would also be beefed up if I do go down this path.
The other issue is data ownership, copyright, use licensing, that sort of thing. Depending on the service and their very detailed terms, you may find that you have signed over ownership and/or use rights to your data with a Cloud service (take Instagram as an example there - far as I'm aware Instagram can still use the photos you upload in any way they see fit, without your consent... because you've already given it... unless they've since changed that detail in their ToS). I know that certain companies don't use Dropbox/other Cloud services for work-related documents for this reason, and certain academic libraries discourage academics from using some of those services for that reason also... particularly when servers are off-shore (International Copyright Law isn't one of my strengths, LOL, but apparently that can create a problem). With a NAS, I don't have that problem. I own the server, I own the files, no one has access to them without my say-so. Simples. LOL.
The one "issue" with a NAS I haven't completely solved is the ability to do an off-site backup of whatever I have stored on my NAS system. Unless I rope a family member into also setting one up. In which case I can tick that off the list as achievable also.
I'd plan to do some kind of local back-up of anything critical on a regular basis too.
I'm definitely not saying I have all the answers. There are a lot of potential downfalls, issues and compromises. But I wouldn't be using the NAS alone as my only "Cloud" option, only back up location, etc. For me this is just the research phase. Reasons why I'd get a NAS won't apply to or suit others. Heck, it may end up being all too difficult and I might not bother, LOL.