If this was in place in the past, the Spurs would not have Dylan Harper. The Pistons would not have Ausar Thompson (they actually went 4 in row - Cade, Ivey, Thompson, Holland). Houston also went 4 in a row with Green, Smith, Thompson, Sheppard. The Cavs would not have Mobley (Garland, Okoro, then Mobley). The Cavs also had 4 in a row with Irving/Thompson, then Waiters, Bennett, Wiggins. The Thunder of years past wouldn't have had Harden as he was after Durant then Westbrook. The Lakers wouldn't have been in position for Lonzo so who knows if thst team takes him or Tatum. And the year prior, the Sixers couldn't have taken Simmons after Embiid and Okafor (they also had a top 5 the next year when they traded 3 with Boston so they could take Fultz at 1). The Suns wouldn't have had Ayton after wasting picks on Bender and Jackson the 2 prior years. Orlando wouldn't have gotten Hezonja in 2015.
I believe that is all of the times a team has had top 5 picks in 3 consecutive years in the last 15 years or so. And the only teams that actually got 3 good players is the Sonics/Thunder with Durant, Westbrook, Harden and Spurs with Wemby, Castle, Harper. It just doesnt happen often and typically when it does, it is because at least 1 of the first 2 doesnt work out if not both of them.