No quotes or text from Culter, though lots of critique of unix: The Unix Haters Handbook

The edit history makes me suspect that this is a personal recollection of someone who was there at the time, and something that was never written down and cannot be verified. It might not even have been fully articulated in the first place, in which case there's only one person who could ever answer.

I agree with JdeBP. Cutler is known for being very private, so you won’t find much that he’s said on the record. I suspect the opinions presented on this Quora question are closer to the mark: he wouldn’t have cared about Unix shortcomings, only those of the systems he’d designed previously (VMS improved on RSX-11M, and Windows NT improved on VMS). Showstoppers! might provide more insight but I don’t have it.

Nothing specific in Showstopper!. p94 (hardback) includes some anonymous team member saying "He (Cutler) thinks Unix is a junk operating system designed by a committee of Ph.D.s There's never been one mind behind the whole thing and it shows." - which sheds little light on I/O issues.

I've known people who come from mainframe backgrounds disparage Unix's sole byte steam view of files because they were used to "richer" file interfaces like ISAM which made certain tasks easier, never mind how inefficient these interfaces could be.

I like asynchronous packet-driven I/O with optional (synchronous) byte streams on top of it. Traditional Unix on disks is synchronous block I/O with byte streams on top of it. The former is more general.

I'm voting to close this question as off-topic because, given the absence of statements in the public record, “What specific or fundamental difference between Unix and VMS or NT was Cutler pillorying?” can only be answered by Cutler himself.

Best information available already sourced as Wikipedia.

TBH I don’t think the Wikipedia entry is accurate on this topic.

You’re right about the choice of venue; but my choice of edit to Wikipedia here would be to delete the mention entirely, since it’s effectively hearsay. The information given in the answer here is useful, although it doesn’t answer the question ;-). I’m not sure we should defer to Wikipedia in general; many of its articles on retro-computing topics are inaccurate, and hard to edit (because corrections get reverted). At least here, multiple answers can co-exist, and readers can decide for themselves what they think is accurate.

VMS is good for Cobol-style record-oriented flat file databases. These databases have the file system as their interface. Multiple applications can be accessing the database files at the same time, hence record locking etc.. are desired. These days, however, we have moved to database applications as a service (e.g. SQL) rather than using the file system as the common access service. Thus, what we need more and more is for the OS to get out of the way while enabling applications each to do highly custom algorithms and data structures, including using their own file structures and formats.

And as far as the “quote” on Wikipedia is concerned, it doesn’t have a citation, which disqualifies it from Wikipedia. That’s what I mean by hearsay (so I used the word inaccurately, yes).

LOL @ "could be debated"

Unix is an old system, that should have been replaced yours ago. Unfortunately it is the most modern system we have, and still years ahead of MS-Windows.It seems to have been at least 10 years ahead of MS for at least the last 30 years (probably longer).