This mentality has always existed.

It's just that back in the old days, game companies did not promote this mentality. They designed content that needed time. Needed long term investment. Community building. Guild management.

So even when people always looked for the most efficient way to do things, it still took time.

But now that game companies are making "products" instead of "games", they purposefully design games to match this fast-food mindset. Hence no more 90 minute dungeons. Everything can be done easily in 30 minutes, which means it can be compressed and done in 10 minutes with an overgeared group.

As the game companies announce that they cater to people who have fragmented play times, speed running and efficiency become the "right" way to do things.

Again, just for emphasis: this kind of thing have always existed, they just wasn't popular enough because game designs back then made it impossible.