That is a speculative argument, not data. While games haven't increased in price the addressable market is exponentially larger. In fact they have probably benefited from keeping the price low.
The reason you see alternative monetization is because it is so damn profitable, not because it is needed simply to fund the games. Look at Warzone, brings in $5.2M per day. There are countless other examples.
Investors want to go where there is maximum profit. But that doesn't mean we need these schemes just for the games to exist.
I think the other reason, besides micotransactions being more profitable, is it's just a better business model for most companies. Having a reasonably predictable regular income is preferable to a one off hit or miss of a single player AAA game.
Companies like Sony still do it, but Sony gets a cut of every transaction on their platform, so they have their regular income as well.
Microsoft has sort of figured out a solution with gamepass where they can make large offers to devs in order to minimise their risk.
If the data is not visible, for an outsider there is no difference between someone making something up and someone making a well-founded argument. Given historical examples, it is more reasonable to assume they are making stuff up. This is what the industry as a whole has always done.
