The outcomes in both cases are now widely viewed as irrelevant, since by the time they were decided, Explorer and Windows Media Player had been overwhelmed by technological change and competition — from Google, among others. Microsoft’s share of the browser and media-player markets is insignificant today.

But even if the European Union’s Microsoft precedent is viewed as sound, Google’s competitive situation is different. “There’s only a superficial resemblance to Microsoft,” said Pinar Akman, director of the Center for Business Law and Practice at the University of Leeds in England, who has received support from Google for some of her research.

Unlike adding a rival media player to the Windows operating system, which at the time was a slow and cumbersome process, adding rival apps to an Android-based phone can be done “in seconds,” said Ms. Akman, an antitrust expert. “The commission put a lot of emphasis on the value of preinstallation. But just because an app is preinstalled doesn’t mean consumers are going to use it. It’s very easy to download a rival app.”

Google’s photo app, for example, has struggled to compete against Instagram and Snap, even though it comes preinstalled on Android-based phones as part of the Google suite.

Christopher L. Sagers, an antitrust professor at Cleveland-Marshall College of Law, agreed that if installing a rival app is as easy as Google claims, “it would make for a pretty solid argument that whatever dominance Google has retained in mobile search has nothing to do with anticompetitive conduct, and rather just reflects its superiority as a product.”

Curiously, the commission’s statement announcing the ruling did not address that issue. (A full written decision is not expected for months.) So I opened the Google Play store on my Android phone and searched for Bing, Microsoft’s search engine. I was able to download it in seconds. Google suggested I “might also like” an array of other search options, including Firefox and DuckDuckGo, which were displayed on the same page and equally accessible with a touch of my finger.

Even though Google requires phone makers to use the full suite of Google apps if they want to install the Play store, there is nothing to prevent those companies from also preinstalling rival apps. “Why doesn’t Microsoft just pay manufacturers to preinstall Bing?” Ms. Akman asked.