Honestly, I think Djokovic at 20 years is very underrated. He was overshadowed because he constantly had to play against Federer and Nadal in their primes, when Djokovic himself was not yet in his prime.
2007-2008 Djokovic faced significantly tougher competition than 2022-2023 Alcaraz. Djokovic had prime Fedal in their mid 20s, whereas Alcaraz has a 36 year old Djokovic who is nearing retirement and is a shadow of the player he was back in 2011-2016.
Let's compare the paths to Grand Slams that Djokovic and Alcaraz had in 2007 and 2023 respectively:
2007 AO - Djokovic was beating everyone except for peak Federer having the best AO run of his life.
2007 RG - Djokovic was beating everyone except for near-prime Nadal. Although I think he would have lost to Federer in the final even if Nadal were absent. But without Fed as well? Yeah, he most likely wins the tournament.
2007 Wimby - Djokovic was beating everyone except for near-prime Nadal, who went on to give peak Federer a run for his money in the final.
2007 USO - Djokovic was beating everyone except for peak Federer, and almost went 2-0 in sets. Carlos would have been destroyed by 2007 Federer at USO.
2023 AO - Alcaraz did not participate.
2023 RG - Alcaraz got cramps mid-match against a 36-year-old Djokovic, whose worst surface is clay. 2007 Fedal on clay would obliterate Carlos.
2023 WB - Alcaraz won this, but he barely managed to win against a 36 year old Djokovic in a very close 5-setter, which could easily have gone either way (also, Djokovic choked a bit on crucial moments). Winning a set against 2007 Nadal at Wimby is easily more impressive than this. And if there were no Federer or Nadal, Djokovic would have very likely won Wimbledon 2007.
2023 USO - Alcaraz lost to Medvedev, and yes, Medvedev played a phenomenal match, but still, 2007 Federer >> 2023 Medvedev.
For Djokovic, he was advancing far into all four Slams and he lost only to prime Fedal. He was easily the 3rd best player in 3/4 Slams in 2007 (I wouldn’t count AO, because he was convincingly knocked out in the 4th round). If prime Fedal did not exist, Nole would have won RG, Wimby and USO that year, along with two Masters 1000 titles which he already won.
As for Alcaraz, he lost to a 36-year-old past-prime Djokovic and Medvedev. He won 2 Masters this season so far, but never had to face anyone on the level of 2007 Fedal. On the other hand, look at Djokovic, who in 2007, beat Nadal AND Federer back-to-back to win Montreal! And don't forget that Nole could have completed the Sunshine Double in 2007, had Nadal not beaten him at Indian Wells. So that's 3 potential Masters 1000 titles in the absence of prime Fedal.
To summarize:
Big Titles that Alcaraz could have won this season in the absence of a prime ATG player - remains the same as it is: Wimbledon, Indian Wells, Madrid - 3
Big Titles that Djokovic could have won in 2007 in the absence of a prime ATG player - RG, Wimbledon, USO, Indian Wells, Miami, Montreal - 6, or possibly even more, because winning all those titles would have given him a serious confidence boost.
20-year old Alcaraz isn't really much better than 20-year old Djokovic. The latter was just unlucky to be overshadowed by prime Fedal before reaching his own prime.
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