The medium matters.
If I tell you I am a designer, this tells you nothing about what media I work in. I might be a clothing designer, or a software designer, or an interior designer, or a digital designer. One of the best things about the moniker “designer” is that it can be fluid, encompassing one or more types of design as appropriate. The flip side of this fluidity can often be the assumption that the medium doesn’t matter: a design is a design is a design.
A crude example shows the fallacy in this assumption: Imagine looking at a design for a dress and being perplexed that the same concept wouldn’t render in bronze as a sculpture.
When the media are more closely related, as in digital and print, the fallacy becomes less obvious. Maybe it’s because so many types of designs begin on paper, but there is a tendency to assume that if it looks good on paper, it will look good on a website, on a mobile app, in a video. People are used to paper. They know what it looks like, they feel comfortable thinking about it. They become enamored with how a design looks on good old paper and refuse to let it transform into what it needs to in order to be the best digital piece it can be.
Embrace the medium. What are the best tools for that medium? What are its strengths and weaknesses? How can I use what exists in one medium as a basis for something completely separate in another medium?