If you have a web browser and Linux, you can often install a .deb just by opening it in Software Centre or other graphical utilities to install apps. The comparison might be someone on windows trusting a random .msi or installer .exe or someone on Mac installing a random .app package. It’s somewhat normal these days. Package managers are sometimes harder to understand and app stores often don’t have the app you want or the newest version. Sometimes the app directs you to the website to install an update - or updates itself from a compromised location.