There are solutions that have been tried and found to work very well. The American shape note system made 3 and 4 part harmony singing something the whole congregation could take part in, rather than just an elite choir. Lars Roverud's digit notation system (and the system to teach it) did a similar thing for singing in Scandinavia. They fell out of favour not because they didn't work, but because professional musicians and teachers saw it as a crutch instead of a system in its own right, and kept pushing for graduating to "real" notation.