Yes, it is behind a paywall, and yes, it is in Swedish, but I'll give you a short resumé:

Since DMA went into force in the EU, Google can no longer show Google Maps as the first result when you do a Google search for an address or place of business. This has led to an increase in traffic to competing sites with 25-35%
The newspaper interviews the CEO of eniro.se which launched their map service back in 1997-1998. According to the CEO, as soon as Google launched Google Maps, traffic to their map service went way down and they could no longer afford investing in R&D for their service. Now, they plan to resume R&D as traffic is steadily rising, up 25% since last year.

This just goes to show that a large portion of internet users do not select a service based on performance or preference, they just click on the first result the search engine shows them (or what service is preinstalled on their device). And when a company is big enough, it can easilly squash any competetition simply by giving their own services preference and then move on to the next area to dominate.
This is the reason Google is prepared to give Apple huge amounts of money to stay as the preselected search engine. Users do not "choose", they "use".
I can agree that it is debateable practice to order a company not to promote their own services, but this prooves that when you reach a certain size, normal competition seems not to apply.
That is why EU DMA legislation is important, and actually make a difference.