There's many cases where that's not true and indeed low-quality bug reports hurt the projects from getting better, specially for mid-to-high popular solo projects.

Think about it in more familiar terms, are more job offers good for searching for a job? It might seems so, but only if you think about well-timed high quality offers. Suddenly getting spammed on your email, linkedin, etc. with dozens+ of low-quality job offers would def not be helpful.