Yahoo was structured wrong from day 1 to ever be great. At the core, it was a company with an unremarkable product that quickly became irrelevant as search engines took over. A directory of the internet was the naive kind of thing that required little skill or vision. That's what Jerry Wang built. That's what Yahoo was. Good idea at the time. Well executed. But not exactly rocket science. And it had a short shelf life and was soon forgotten.

But it had money courtesy of lots of pre-dot com bubble stupid money that investors were flinging around. So it bought things that others had built to grow. And for a while that worked.

It had more resources and toys than Google. But over time Google outperformed them on essentially everything it bothered doing. Better search engine, better mail, better news, better video (twice because Google Video was better than Yahoo Video before Youtube dethroned it), etc. These are all areas where Yahoo belatedly tried to gain ground through acquisitions and failed; over and over again. They always came in second or third with essentially anything they touched or tried.

By the time Marissa Mayer (ex Google) came in, Google had already won and Yahoo was this big stupid conglomerate of many things that were kind of alright individually but clearly never going to add up to Google. And the rest is history. Marissa Mayer flailed for a few years. There were more acquisitions and a few flopped projects ran by her personally. None of it mattered.

In the process, they ran Flickr into the ground. They ran Tumblr into the ground. Etc. They built a well deserved reputation of poor stewards of great stuff that landed in their laps. What they bought was quality. But they couldn't maintain that quality or nurture it.

Yahoo is a great story how all the money in the world can't make you a great company if you start out being a mediocre also-ran. If you are running blind, because you have no vision, deals like Google and Facebook will woosh right by you. That's what happened. And arguably, it wouldn't have mattered, because they'd likely have screwed those companies up as well.

A human-curated directory of the good parts of internet would be worth it's servers weight in gold today.

Combine with modern perplexity-style answer engine and it would be far away from "also ran".

Yahoo! had 99 problems, but human curation wasn't one.