A recent Twitter post make the false claim that. I won't embarrass the OP, since he seems to delight in making such unsubstituted claims.
As an early user of (a FORTRAN 77 developer on Software Intensive System of Systems for Ballistic Missle Defense systems) the principles of Iterative and incremental development, emergent requirements, customer in the loop, and other principles, practices, and processes found in Agile started long before the Agile Manifesto, in 2001.
Let's start with a history paper, “Iterative and Incremental Development: A Brief History,” Craig Larman and Victor Basili, IEEE Computer, June 2003.
And here's another "Iterative Enhancement: A Practical Technique for Software Development," Victor R. Basil and Albert J. Turner, IEEE Transactions on Software Engineering, Vol. SE-l, No.4, December 1975.
And another from early on in complex systems development "Design, Development, Integration: Space Shuttle Primary Flight Software System," William A. Madden and Kyle Y. Rone, Communications of the ACM, Volume 27, Number 9, September 1984.
These are a few of many papers describing how iterative and incremental development used - long before the Agile Manifesto and eXtreme Programming.
Then let's look at the actual description of how iterative and incremental development took place in “Managing the Development of Reliable Software,” R. D., Williams, Proceedings of the International Conference on Reliable Software, April 21-23, 1975. You'll need an ACM membership (which I doubt the OP has) to read this one. But notice in the Larman paper that IID started in 1936 and has evolved ever since.
Another paper, where I have hands-on experience is "TRW's ADA Process Model for Incremental Development of Large Software Systems," Walker Royce, TRW Systems Integration Group, Space & Defense Sector, Redondo Beach, CA, describing the development of the Command Center Processing and Display System-Replacement (CCPDS-R) project's success in with over 300,000 lines of Ada source code executing in a distributed VAX VMS environment. The VAX is my favorite real-time computer, by the way. Again a membership to IEEE is needed, not likely the OP has one.
I've since lost my handbook issued at TRW for the Software Development Lifecycle processes used on the programs we worked, but the loop approach of plan, do, study, act was at the heart of that method. And of course, the classic misused and misquoted paper that agilest use as the stalking horse for their claim iterative and incremental is the replacement for the dreaded Waterfall process is Winson Royce's "Managing the Development of Large Software Systems," WESCON, August 1970. By large Royce means large. Defense systems.
Is this early work the same in form as Scrum, XP, or other Agile development methods? Not exactly. Are the principles the same? Yes, pretty close.
But of course, the Agile Manifesto is not actionable in any practical way, as the 12 Principles is.
So when the OP claims that the same folks that branded #Agile as not professional did the same for #NoEstimates - it's patently false. Those that objected to the early XP approaches - and I had an email spat with Ron over how to release partial features to a production system where those partial features were missing the core elements of the needed Capabilities - were right to criticize the lack of governance and actionable outcomes.
Since we and I was one of them, saw XP as essentially hacking in the absence of those governance processes. Now put a governance wrapper around XP and you get a useful approach to develop emergent software and here's the paper that shows how to do that in 2003.
The criticism of #NoEstimates is simple
You cannot make an informed decision in the presence of uncertainty without estimating the impact of that decision.
To claim otherwise willfully ignores the principles of managerial finance and probabilistic decision-making.