NJ isn't quite as loaded as you think, and they probably stopped their rebuild a year or two early.
They also got lucky with two #1 picks.
Nico (25), J Hughes (22), Bratt (25), J Hughes (22), L Hughes (20)
they have Nemec D (20) Casey D (19) and Holtz LW (22) on the way
But also had to fill out their roster with free agents and trades
Hamilton (30), Meier (27), Marino (27), Palat (32), Haula (32), Toffoli (31), Miller (31), Nosek (31), B Smith (34)
Meier - 2023 1st, 2024 1st
Marino - 2023 3rd, Ty Smith
Toffoli - 2023 3rd
Haula - Zacha
Lazar - 2024 4th
Vanacek - w/ #46 for #37 & #70 in 2022
Since 2015 they had #6 Zacha, #12 McLeod, #1 Hischier, #17 Smith, #1 Hughes, #7 Holtz, #18 Mercer, #20 Mukhakmadulin, #4 Hughes, #29 Stillman, #2 Nemec.
They took so long simply b/c they didn't draft well, if they weren't lucky, they'd still be wandering in the wilderness.