He was an academic.
Did he anticipate user demand, market forces or that a corporation (Google, Microsoft, Hashcorp) could drive a permissive licensed open source project in the open?
It turns out the Firefox and Chromium, both liberally licensed projects, usurped Internet Explorer's monopoly on browsers. Both ultimately are backed financially by corporations with huge troths of patents and proprietary code.
As for Firefox, the Mozilla Public License is actually a (weak) copyleft license, since if you modify any file, you must distribute your changes - it's closer to the LGPL than to MIT/BSD. And the other licenses under which Firefox is distributed (it's tri-licensed) are GPL and LGPL.
Chromium is permissively licensed, and Chrome integrates proprietary components. Strengthening the product with features and giving it marketing.
I see the point on MPL. As for bundling more restrictive licenses - as a developer - you have to judge by the most permissive to see how free it really is.
> SHARE Inc. is a volunteer-run user group for IBM mainframe computers that was founded in 1955 by Los Angeles-area users of the IBM 701 computer system. ... A major resource of SHARE from the beginning was the SHARE library. Originally, IBM distributed its operating systems in source form[1][2][3] and systems programmers commonly made small local additions or modifications and exchanged them with other users. The SHARE library and the process of distributed development it fostered was one of the major origins of open source software.