I've always believed that working for someone else's company allows for little to no creativity.
At best, you're told what to create/design, when to do it by and pretty much what the end result needs to look like. That isn't real creativity because a true artist has ultimate control over the creative direction their work takes. When you work for someone else, even if you're the chief designer for Apple, your creative energy is directed and managed.
At worst - and this is applicable to the vast majority of jobs - you just have to get things done. It's all about output and results. Creativity is reserved for weekends when you engage your hobby of landscaping or painting. Most jobs are about output, not innovation. (Improving a SAP report or presentation template cannot be called true creativity.)
In fact the below infographic based on Adobe's State of Create study is probably understating the lack of creativity there is in the workplace. The stand out statistic nonetheless is that 75% of people surveyed said they are under pressure to produce rather than create. There's a huge difference between the two.
In a company you're hired to help meet an overall objective. Your fancy ideas usually translates into a deviation from this objective. Besides getting a hobby, the only way to genuinely tap your creative juices is to employ yourself.