What's So Bad About Modern Office File Encryption?

I use Keepass to store all my login credentials. I've read numerous articles about never, ever saving login credentials in an office spreadsheet or document. But, under the hood, apps such as Keepass, 7-zip, Office 2013(+) all 'boast' AES-128 or AES-256 encryption, no? So, is there really a significant security difference between these apps and file formats - when at rest?

And when open and in use...dedicated password managers like Keepass won't leave passwords on Windows clipboard - wheareas a spreadsheet or doc user NEEDS to remember to clear the Win clipboard. That can be a critical weakness, but most of us don't share our laptops... and if we are careful about securing our laptop / devices anyway? Because if someone takes control of our laptop / device, no app and no data is safe anyway, correct?

As mentioned, I use Keepass - but playing devil's advocate here. The dire warnings against listing out your login's using an encrypted Excel spreadsheet... heck, company staffers keep all kinds of confidential data in their spreadsheets/docs, no?

 

The assumption is no one is protecting the excel sheet that contains their passwords.

 

Yeah, I suspect that modern Excel, Word, Keepass, etc. -- if used and protected properly -- are all pretty secure (meaning for everyday folks, not for those specifically targeted by the CIA or NSA). I haven't come across reports of data files systemetically crackable by any 3rd party tools, regardless of password length/complexity - like the encryptions of old (e.g. Office 95).