It's actually not! It will work fine. Linear history is one strategy for using git (and it's a reasonable one), but try introducing (manual, planned, not done with git pull) merges sometime, at points where the actual intent of the maintainer is to perform a merge - you may be pleasantly surprised. (If you use the program naively you will eventually confuse the algorithm, which may have bitten you in the past - forcing linearity is way better than naive use.)

See https://mirrors.edge.kernel.org/pub/software/scm/git/docs/gi... for more info