Famed computer scientist Niklaus Wirth has passed away, just a few weeks before reaching his 90th birthday https://www.theregister.com/2024/01/04/niklaus_wirth_obituary/. He is known for being a champion of simplicity in programming language and system design. He had a falling out with the committee that was coming up with a successor to Algol-60 (itself a driver for many important language-implementation techniques), and so went off and created Pascal. And then a few more languages after that.

In his criticism of the language, Algol-68, that the committee eventually came up with, I found this excerpt illuminating on the milieu of the time:

I am discouraged! I thought I had recognized the short-comings of the commercially available languages; they provide no guidance to programming discipline, and lack a logically coherent structure. Algol 60 had provided an answer and a solution. Unfortunately, it lacked some features which many practitioners badly need. It was relatively easy to remedy some defects and some defaults of Algol 60. We had implemented such an extension of Algol; it contains the data types long real, complex, and character strings, along with one other major extension. But guess how many requests we received for this system. None! Nobody is interested in a new language, particuarly if it is not supported by the big manufacturers or has received the blessing of some standards committee. But I see no chances that either a big manufacturer or a committee will ever produce a language acceptable to our standards or clarity, simplicity, and rigor.

Remember, this was published in November 1968.

Notice the assumption that the only sort of language implementation that might be worth using is a “commercially-available” one, with the backing of a “big” company behind it. There was no thought that an implementation with source code freely available could ever be considered “commercial”, either in usage or quality.

And on top of that, every OS was different; there was nothing like the near-universality of POSIX-type OSes we enjoy today. And some of the differences were downright--quirky, shall we say. So even if such a source code project were available, porting it to all the platforms in common use would likely have been a nightmare.