I'd break this argument into 2-3 parts, all of which I disagree with to some extent.

1. Gods need to be released as OP (or at least above the point of balance) because if they were released at the point of balance people would underperform with the god and not play them anymore because they don't find it fun, and the game as a whole would suffer.

First off, this somehow implies that if the god is released at above the point of balance, people being new to playing the god will be inexperienced with them and thus play them at the point of balance. This is just not true if you are level 30 with decent elo. After about a day of the god being out, every game will just get ruined by someone playing the new god at an at least decent level (Bellona, Ao Kuang, Nemesis, Sol, etc). It honestly doesn't take that many games for experienced level 30 players to get a decent grasp on a god. Some of these gods (hi Bellona) stay at this state for AGES, even hitting ranked, before they are tuned properly, and turn people away from the game because they don't like getting 1v4ed every game by a rank X broken god spammer. If a god came out at a glorious state of balance, people may underperform with them for a few games, but to suggest that a balanced god would be seen as inferior and ignored by the community is ludicrous. The community would adapt in a day or so (talking level 30 community here). Which do we think gets more people to stop playing Smite: Sol and Bellona being total trololol game ruiners for weeks, or an uninspiring, underpowered god coming out very rarely like Cabrakan or Ravana? Answer that question honestly for me.

1. If a god is released below the point of balance, even if they get buffed to a good spot, people will not play them because there is a stigma about playing the god, or the god just doesn't generate excitement.

There is just not enough evidence to support this. There have been 2 gods that have come out underpowered as far as I can remember, Cabrakan and Ravana (Hou Yi was more wonky thank underpowered, but he doesn't back up Diem's point either way). When Ravana was reworked/buffed, he was played a LOT, as he was insanely strong. He was nerfed rather quickly afterwards though, which predictably reduced his playing time, while additionally other warriors rose to prominence (Guan) while stronger warriors came out to replace him (Amaterasu). Cabrakan was played even more so when he was buffed. Jungle Cabrakan was played in high level SPL games often, and solo Cabrakan was a force as well. Saying that if a god comes out underpowered and is then buffed, that they will not get paid attention or played enough, is simply not supported by the limited evidence we have via underpowered releases.

1. Power creep is necessary because a game must be kept fresh to draw players in, and to keep it fresh new mechanics must be introduced, which will (sometimes) be much stronger than old mechanics. If you don't think he said this go back to the second half of the video and listen again.

Or we could just introduce new mechanics that are at the same level as old mechanics in terms of strength? Why must new mechanics be inherently stronger, and why can't they be tuned down to stop the flow of power creep? Also, not all power creep is from new mechanics. When the top dmg Yu-Gi-Oh 4 star has 1600 ATK, and then a card comes out with 1700, then 1800, then 199, then 2000, that isn't any sort of new mechanics, it's just blatant power creep to force you to buy new cards. Or when Rageki comes out and you can just destroy every single opponents' monster and it doesn't even need a trigger like Mirror Force. That's not some "enticing new mechanic", it's just a blatantly overpowered card that shits on older cards like Dark Hole. Justifying power creep by saying new mechanics must be stronger than old ones just doesn't hold water under scrutiny. Skadii's ice is a new mechanic, but it doesn't break the game and she won't be viable competitively (no mobility). Bellona had half a dozen new mechanics, but they didn't need to be "inherently stronger", the numbers were just too strong, and she eventually got brought more in line with balance (although it took forever, still salty over Bellona...)

While I do not believe the accusations of Erez sexually harrassing employees, or being a tyrant over new god balance like the ex-employee states, I disagree with most of the points in this video.

As a closer, at one point in this video Diem says "...because of well-crafted Youtube videos with eloquent speaking that make you think that their opinion is fact. It's not." I've never seen such a statement ring more true with Diem himself. Diem IS incredibly knowledgeable and has a deep background in gaming, but acts as if he is the only one, and has a tendency to preach his opinions as hard facts (and if you don't agree with him, you're stupid, and he's gonna tell you why.)

There's also an egregious amount of flaws during the segment he was talking about WoW, but this comment has gone on long enough.