The risks are higher than the (potential) gains. The output of the analysis is not only a factor of the code itself, it also depends on which rules are enabled in the Quality Profile, what are the analysis settings etc etc. Even if code doesn’t change, then the analysis report can greatly vary if rules/settings/parameters were modified.
Also never forget that even if a file did not change, there could still be a new issue in that file: think of a function now deprecated in fileA , if fileB uses that method then it would raise a do not use deprecated method issue, even if fileB did not change. That’s the basic example, only to illustrate that (on top of the influence of server-side project settings) focusing on changed files is also not enough for any advanced analyzer that does some detailed/cross-file inspection (which many SonarAnalyzers do).