+50 isn't any better than +30, since both mean auto-success on any skill roll. Both are game breaking, and make skill monkey characters redundant. Skill checks of over 30 are meant to represent the virtually impossible, like swimming an ocean or persuading a dragon to give you all it's gold. Something the DM might be happy for a highly specialised skill-based character to have a chance at with magical assistance and a lucky roll, not something a guy with a magic bite can do automatically.
It's pretty easy to get to silly numbers on a weapon damage roll. Paladin smite, Battlemaster manoeuvres, Enlarge, Rune Knight Giant's Might, etc etc. And you don't need to get to +50 to break the game, +15 is enough to equal the most skilled rogue.
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First, a d4 or d8 plus mod as a bonus to a skill check is already doable without the Dhampir's bite. Advantage, plus guidance, plus bardic inspiration, plus certain battle master maneuvers, plus enhance ability, plus expertise, plus reliable talent... you can already get high numbers fairly easily.
Additionally, a number of people have already stated and acknowledged that limiting the bonus to the base weapon damage is probably the intent and balanced. This includes my post which you quoted above, but seem to have conveniently left out and did not acknowledge.
Also, it has also been mentioned, including by me, that there are no auto successes in 5e like their were in 3x. Just because you have a high bonus or even a natural 20, that does not mean you succeed. No matter how high your roll, you aren't going to convince a dragon to give you their hoard. And a reasonable DM won't even let you attempt that check, even with a +50 bonus to the relevant ability/skill.
I'm starting to wonder if you are approaching this conversation and arguing in good faith, or simply looking to repeat how much you hate high bonuses. The original post was asking about the balance concerns of combining the Dhampir's bite with the Path of the Beast barbarian's bite. It's not about whether high skill check bonuses are game breaking (which I don't think they are if the game is being run by a reasonable DM).