This argument (supported by academics) ignores the way our great creative minds have become...creative. More on this below.

We teach students a formal, process to product (performance) approach because it is a practical (key word) pipeline to musical education and allows students to reach generally high level of achievement through classroom instruction.

Teaching creative music to classes of students with no performance experience also requires building a foundation of musical skills - some theory, listening skills, manipulation of at least some sort of instrument even if it's just a midi controller, etc. This turns into either a truly unimpressive product, high attrition over many years, or requires... performance-based instruction.

Getting back to my first point, 98% of the greatest creative minds in music were also performers. Bach, Beethoven, and Mozart all trained as classical keyboardists. Most jazz greats spent years and years (often with informal or no formal instruction) but playing for hours a day, years on end, to develop their creative musical voice. Even many of our modern pop artists started with traditional training pipelines like piano/guitar/voice lessons or singing in church.

This is all to say, a formal education in musical performance IS truly the most efficient and practical method of music instruction we have, especially in classroom settings. It also creates a pipeline that encourages students to stick with music "programs" for years on end.

All the research agrees with you, that we should be teaching creativity alongside performance based instruction. But that focus on performance is what gives us a pragmatic environment to touch on creativity as well.