You know it's not really all that difficult to see the writing on the wall for some technologies.
Flash in particular you could see coming from a mile off. It was a web browser plugin that hated the web. It tried its best to fight against web technologies at every turn. Many aspects of the web - URLs for discrete resources, the DOM for discrete page elements, source-based delivery, cross-platform authoring, open-source authoring, etc. - were actively subverted by Flash. So all the forward progress for the web that improved or relied on these things fell by the wayside for Flash.
Likewise with PHP frameworks. With few exceptions mainly relating to lock-in, everybody who's got any taste and skill abandoned PHP years ago or never took it up in the first place. As a consequence, this leaves the people driving PHP forward very poor stewards. PHP is a zombie at this point - the killing blow has already been struck, it's already dead, it's just going to take a while for this to become so obvious it cannot be ignored. Competent people don't do things like cause security issues because they make releases after ignore failing tests.
You say that you deliberately eschewed open-source, but if you look at where the forward progress for the web has been coming from, it's predominantly open-source projects.
I just don't see how you can have any understanding of this industry and continue to make those kinds of choices.