Fiddlesticks in every season previous to this one says Hi.
It's not the lv 3 Dragon that's problematic (that gimmick has been in the game on one champ or another for years)
It's the level 1/2 dragon, plus the insanely broken rank 1 dragon buff that's the problem.
Oh, it's 4 minutes or so into the game, and oh look 8% additional AD/AP, thanks pantheon.
If the first buff was %bonus damage to minions or something, it would be less of an issue. 8% AD/AP is basically a few hundred free gold for your entire team, it's worth more than old dragon stat-wise.
8% of 60 AD is 4.8, so every non-AD scaling champ just got 180g of free stats, not including any bonus AP.
Your carry and AD champs probably have about 70-80 or more. at 100 AD they get 360g worth of stats (free longsword.)
That's worth more than old dragon EASILY, and that's not OK. It gets even worse, because that advantage is insurmountable until the next dragon spawn, and if Pantheon's team is at all competent they'll secure that dragon too, snowballing even further.
That's not to say Dragon buff early on is gamebreaking, but it's a slippery slope that needs to be de-iced.