Most of the stupidest shit in hacking is programmers reinventing wheels. The new wheels start out square, and eventually become round. Sometimes the process of becoming round takes a very long time. CSS is one obvious example, but you see it over and over — in GUIs, in distributed systems, in language design, and everywhere else.
Avoiding the mistakes of the past is a very old problem with a very old solution: listen to people who have been there before. But old people are pushed out of the tech industry, where "old" means "over 30." I think there are two main reasons for this.
First, Moore's Law pushes virtually everything to become a computer. To computerize any given thing becomes cheaper and cheaper with every passing moment, and most things become more useful with the change. But as every object becomes computerized, the demand for programmers grows and grows, and it really shows no sign of stopping for quite a while.
It may slow or disappear altogether once computers learn to write code for themselves, but it may not. At the very minimum, the black market for illegal hacks will grow and grow and grow, irrespective of who wrote the systems being hacked, or indeed who wrote the hacks.
For the forseeable future, because each generation is "always" larger than the one which came before it, it's going to be a truism that programming will "always" seem overrun with kids. But because people are very prone to stereotyping and overestimating the importance of successful flukes, a field overrun with young people is a great petri dish for cultivating ageism.
And venture capital exacerbates this problem. They're gamblers. They like to think they bet on likely winners, but it's more accurate to say they bet on what they perceive as likely winners. In other words, they go for young white men from Ivy League universities, not because those individuals truly have any higher probability of success, because venture capitalists are human, and they're as susceptible to logical fallacies, stereotyping, and superstition as the rest of us.
But they're more influential than the rest of us. So, like their sexism, their racism, and their tendency to chase shallow fads, their ageism becomes the industry's ageism.
To be clear, they're not responsible for all of it. There are built-in factors which make ageism highly likely, if not necessarily inevitable.
But they make it worse. They hire young people straight out of college to reinvent wheels, badly, in huge numbers.
And keep in mind that Moore's Law is almost a force of nature, while venture capitalists are a group of people. Of the two forces that are making us stupid, one of them can be reasoned with (relatively speaking, at least).
I don't think these trends are very likely to dissipate, but it's worth it to try and get some sense into their heads. And if you're a VC looking for an edge, I have good news: wisdom is inherently valuable, yet it has a terrible marketing problem, and will probably continue to do so for your entire lifetime.