We have 22,000 employees globally. IT is not going to give random humans access to a service account.
The biggest issue I have is that all the material for Flow is totally geared towards "citizen developers" and business users for business processes automation. Read the whitepaper in Chris' original post. To paraphrase, "Citizen developers can use these business apps to automate processes like on-boarding and travel approvals". Makes it sound so easy, anyone can do it. And they do.
None of this material comes with a SINGLE WORD OF WARNING that the process could come to a grinding halt if there is the smallest problem with the credentials of a single user. And last I heard, if a Flow stops running due to problems with credentials, there is NO WARNING to the user, other owners, etc.
This is a massive risk to business continuity that no one mentions.