Anecdotal evidence is all well and good, but virtually all studies of admissions have determined that legacy status provides a significant boost at highly selective colleges.
To use Harvard as an example, see the recent study below.
The estimated coefficients on indicators for legacy, double legacy (i.e. both parents are alumni), faculty or staff child, and being on the dean’s interest list are all large, positive, and statistically significant… consider a white typical applicant with a baseline probability of admission of 10%. If this applicant were switched to a legacy, holding all other characteristics fixed, the admission probability would rise to 49%. Switching the same typical applicant to a double legacy or dean’s list member would increase the likelihood of admission to 65% and 75%, respectively…
we estimate a model of Harvard admissions that accounts for hundreds of applicant characteristics, including Harvard’s academic, extracurricular, and athletic ratings, among others. Admissions preferences for ALDC applicants are substantial. We find that a white typical applicant with a 10% chance of admission would see a five-fold increase in admissions likelihood if they were a legacy; more than a seven-fold increase if they were on the dean’s interest list; and that they would be admitted with near certainty if they were a recruited athlete.