Tera Blast is just a more fun version of Hidden Power because it's more powerful, works for both attacking stats, doesn't require IV fuckery, and is obviously attached to Tera, which I feel is a generally fun mechanic.
Plus, it requiring Tera also allows some niche interactions such as just acting as extra Hyper Voice PP on Sylveon.
Also Tera changing your type makes those sort of "You switched in this mon? You fool!" interactions play out far more consistently due to the whole concept of the type you Tera into to hit the thing you're normally weak to typically not also being weak to it (and sometimes even resisting it).
Anyways that's my TED Talk on why Tera is fun as fuck and should never be banned.
Especially since if Tera were banned, it would make nearly all tiering action done across all tiers (save for perhaps bans to AG) entirely null and void.
Plus, banning Tera would make the game way more one-dimensional, which, if you want a more one-dimensional modern generation, you'll never guess what number immediately precedes 9.
And even just banning Tera Blast (an idea I've seen tossed around) wouldn't work too well.
If there HAS to be a full ban regarding the Tera mechanic, I'd much rather it be Tera Blast, but removing Tera Blast still removes a lot of fun counterplay.
For instance, I run Pixilate Sylveon in SV OU (because I'm a dumbass). I run Tera Fire on it to hit Gholdengo (even with Air Balloon) and most other Steel types in the tier, including those such as Corviknight that may otherwise fuck over my whole team.
If I ran Tera Ground, I'd have to trade off hitting Air Balloon Gholdengo (a set that has annoyingly increased in popularity and the same that it was originally built to counter btw) for hitting Heatran and various other Ground-weak mons.
But then again I could just switch in my Mudsdale (still a dumbass) and force most of those out without expending my Tera.
The reason Tera Fire works better imo for Sylveon is that not only does it resist Steel, but it also is resisted by fewer secondary types of said Steel-types, whereas many Steel-types have secondary types (or items) that make them resistant or immune to Ground and Fighting.
And Tera Fire only fails against most Heatran sets, and I don't even think Heatran's that popular in OU currently, especially compared to the likes of Gholdengo and Kingambit.
Another case of Tera Blast being greatly helpful is Iron Moth.
Iron Moth's 4x weakness to Ground (that isn't helped by Air Balloon, since it typically would prefer to run Booster Energy or Choice Specs/Scarf) is a huge detriment, especially for what is currently the "6th slot mon of the week", if you will.
Its weakness is even further compounded by how prevalent Gliscor is, a Pokémon that my team pretty much is guaranteed to lose to.
So, there's some nuance between Tera Water, which is overly better against a fair amount of the rest of the tier, but can sometimes miss out on the OHKO on Gliscor if you're investing into Booster Energy Speed, and Tera Ice, which defensively crumbles to Steel, a fairly prevalent type, but does guarantee the OHKO on Gliscor.
But what even is so powerful about Gliscor that leads 90% of my team to lose to it?
Gliscor's sheer bulk and pretty good defensive typing makes it hard to kill as is, but it also gets both Poison Heal and Protect, which fundamentally means that it CANNOT DIE unless you at least 2HKO it. And this is far more powerful than if it just had access to, say, Recover, because Recover only has 8 PP as opposed to Protect's 16, and to achieve the same effective health gain per damagable turn, you'd have to spam Recover non-stop, whereas Gliscor is able to use other moves in between.
And that's even before you think about the fundamental fact that Protect makes you immune to nearly all effects for the full turn, so it even helps you scout out the enemy's moves. And because of that, even if you DO have a Gliscor counter that can OHKO it, you have to make sure (by which I mean just hope) that it doesn't Protect on that turn, because then they know of your counter and can just switch out their Gliscor.
And since Gliscor tends to run Toxic Orb to activate Poison Heal, it's not like you can just burn it. And since it also tends to run Toxic, you can't just stall for 32 turns until it runs out of Protect uses and you become able to kill it with moves that at least 4HKO. And it running Toxic also gives it a relatively non-committal option to put any offensive threats on a ticking timer, allowing it to just sit back and protect every other turn while you waste the PP of, for instance, Ogerpon-Wellspring's Ivy Cudgel. And you can't just switch in a Poison or Steel type such as Iron Moth or Kingambit because it runs Earthquake, so any earthbound Poison or Steel types just get fucked by that.
And on TOP of ALL OF THAT, it gets Spikes, so you can't even just repeatedly switch shit around to waste its Toxic, Earthquake, or Protect PP.
In conclusion, Gliscor cannot die.