You’re right. All those moves really hinder Ursa’s ability to do well. Even its special defense is very easily exploitable. However, Ursa has already started to adapt to these:

Ursaluna-Bloodmoon @ Leftovers
Ability: Mind's Eye
Tera Type: Normal
EVs: 248 HP / 56 SpA / 164 SpD / 40 Spe
Modest Nature
IVs: 0 Atk
- Blood Moon
- Hyper Voice
- Vacuum Wave
- Calm Mind
This is my set that I’ve been using along with Alolan Ninetales for screens support. It got me up to 1900s and achieved a 35-3 record for voting reqs. Here’s how the set handles each of the aforementioned issues:
1.
Taunt: Common taunters are frail and cannot risk staying in on Ursa before getting nuked by Blood Moon. Usually, you can get +1 before getting taunted, and even when taunted, it really isn’t a big deal. Just click your moves and watch the other team fall apart.
2.
Encore: This is definitely the best counter measure to Ursa, just as it is against any slow setup mon. Here’s the issue: you have to know what the Ursa is going to do. If you encore an Ursa into Blood Moon, it goes for it repeatedly and doesn’t have a cooldown (I found this out the hard way). If you hard switch into Ursa with your encore mon thinking it will CM and it uses Blood Moon, you just lost your encore mon and really don’t have counterplay for Ursa setting up. It’s not a bad option, but it’s not consistent enough and relies on prediction to succeed. Even then, I could see Ursa running Mental Herb to avoid this issue; I won’t count it here though since I never see that.
3.
Protect: My set accounts for Protect. By running both Blood Moon and Hyper Voice, Ursa does not need to second guess clicking Blood Moon as often. If it doesn’t work for Ursa, you just Hyper Voice the next turn and do great damage; if it’s not quite enough to KO, you have Vacuum Wave in a pinch.
4.
Substitute: Beyond not having to worry about clicking Blood Moon, my Ursa set having Hyper Voice completely ignores any Substitute user barring Soundproof Kommo-o. Even on normal sets with Blood Moon as the only Normal attack, Substitute would only be viable on Flying-types and Levitate mons so that they can’t be chunked by Earth Power.
5.
Weak Special Defense: Having investment in bulk, access to Calm Mind, and protection from screens fixes Ursa’s most glaring weakness. Screens especially makes Ursa live every hit with ease.
I see the argument you’re trying to make, it’s just that none of these moves fully counter Ursa. In fact, nothing fully counters Ursa; there are only checks, and a well-made team can easily handle such checks.
I’ll link the team
here if you want to try it out. Let me know if it changes your opinion on Blood Bear, it did for me