Being a responsible programmer/sys admin has always been read heavy, as long as I've been alive. Write only code is antithetical to the basis of running a trustworthy system.
The Web is a rather different beast, but the question is not "can you trust the Internet", but "can you trust a random website", and now even "can you trust a previously trustworthy website".
You of course should not trust any pictures or videos as critical evidence, they should be corroborated by other means. But this has been true for several years now.
I assume you mean software, because we haven't been trusting other things on the web already for decades.
As for software, everybody interested knew about inherent insecurity of supply chain of modern software but the solutions proposed were too expensive. We need an order of magnitude more money lost for organizations to start switching from today's security theater to a model with security built in.
Even though we were aware of the insecurity of the supply chain, 1) In practice we tend to ignore it except for mission critical cases. We still do. 2) Autonomous vulnerability/exploitation at scale was difficult and reserved for high value targets.
What you said will be accelerated by 2) now.
Not in this world. It would create friction in the money printing machines.