Sure, but would he have won the GRAND SLAM, the greatest achievement in tennis? No. Let alone doing it twice, something nobody even in the much less competitive WTA has ever done, and the second time at 31 years old after being banned from playing the slams for 5 years. So even with 19 slams, Laver > Federer.
Also if we want to go into what ifs, Laver, Rosewall, Gonzales, possibly Tilden and Budge would all have over 20 slams if people played all 4 slams, all the time, until they retired from tennis completely. Sampras and Federer would have never held the record. Someone like Connors would even be up with Sampras in slam wins, rather than tied with Agassi.