I don't really agree with this. It is the answer that I think classical economics would give but I just don't think it's useful. For one, it ignores politics. Large corporations also have bought our government, and a few large wealth management funds like vanguard own a de facto controlling share in many public companies, oftentimes including virtually an entire industry, such that competition between them isn't really incentived as much as financial shenanigans and other Jack Welch style shit.

Some scholars (i think I read this in Adrienne bullers value of a whale, which is basically basis for this entire comment) even argue that we've reached a point where it might be more useful to think of our economy as a planned economy, but planned by finance instead of a state central authority.

All that is to say: why would we expect competition to grow, as you suggest, when the current companies already won, and therefore have the power to crush competition? They've already dismantled so many of the antimonopoly and other regulations standing in their way. The classical economics argument treats these new better companies as just sorta rising out of the aether but in reality there's a whole political context that is probably worth considering.

I disagree on your expectations for improvement, though agree on the rest.

There are lots of markets with natural barriers to entry were there isn't any realistic chance for a new competitor to arrise and even if one did thanks to, say, some new technology, they'll almost certainly only "disrupt" until they became well established and then do the same as all the rest because that maximizes profitability (just look at Uber a decade ago and look at Uber now).

Then there are lots of markets were crooked politcians (which nowadys seems to be most of the ones in the mainstream parties) make sure there are artificial barriers to entry so that well-connected companies are protected from competition - pretty much any market were an operating license is required, such as Banking and Mobile works like that - and that too means no costumer-friendly competitors will arrise in such markets, ever, because the gatekeeping which is in the hands of said crooked politians stops them before they even start, and said political gatekeepers couldn't care less about consumer-friendliness of market participants and they'll only change their ways if forced to politically and that's not going to happen in countries with voting systems designed to maintain a political duopoly such as the US were the politicians rarelly fear losing their positions, especially on complex hard to explain things like how consumers suffer from them "maintaing high artifical market barriers to entry"

In the old days, before neoliberalism got entrenched, you might have such natural or artificial monopoly or cartel markets occupied by a Public company, which due to the lack of competition quickly grew inneficient (in my professional experience the same happens in Private companies in such a situation, by the way), though cheap, and on which there was often political pressure to improve. Now you have them occupied by Private companies who are driven solely by profit-seeking, so it's still shit (because they cut costs) only it's also expensive for customers rather than cheap (because they try to squeeze costumers with high prices) and suffers zero political pressure because the politicians hide behind the "It's a Free Market" to refuse to regulate whilst secretly waiting for their Non-executive board memberships as rewards for being "friends of business" - a wonderful example of all this are Railways in the UK.