Razor leaf is like having hundreds of knives thrown at you simultaneously. Hydro pump you basically die almost instantly. There’s a reason water jet can be used to cut metals.
A firehose for comparison is usually minimum 200psi. Close up would hurt really badly but the chances of dying aren't great. At 20ft away you'll just get really wet. Their numbers aren't wrong but the analysis of what the numbers mean is probably pessimistic for the Charizard.
The OG Pokemon was so unbalanced and had such a huge bias in favor of Grass types that I legitimately don't understand why anybody would pick the other two unless they were doing a challenge run.
And fire types SUCK SO BAD. They can't kill anything. They don't even do that much damage to the grass types who just Leech Seed them all to death.