There is a reason 5e toned down that sort of thing. What happens when the party doesn’t have those damage types? Or they do have them but don’t know that? Then your encounter balance calculations are completely off.
Unless you are going to take a monster of the week approach and give the party the opportunity to research the monster before the encounter.
Oh I know I can't go heavy into this, believe me, picking on players who don't have access to a given element is bad form, as is making someone randomly resistant or immune to your damage type of choice- I've long hated how "martials" don't typically have any access to elemental damage and how the best damage spells for casters are commonly resisted types, or how the game is pretty mean to "themed" spellcasters.
But the flipside is, I've just come off a campaign where, by level 9, most damage types are only important in that they actually effect the thing we're fighting at the moment. A few of the players have attacks that deal multiple types of damage, and we always have to ask "hey does it matter that I'm doing piercing and X?" and typically the DM says "no not really, just add it up". Our group does bludgeoning, slashing, piercing, force, radiant, necrotic, poison, and with my Wizard, the occasional fire/cold/acid spell. And generally all that means is "most things are resistant to bludgeoning/slashing/piercing if you don't have a magic weapon", necrotic and poison suck to use, and the only benefit to radiant is "it's not those other damage types", and the benefit of force is "it's better than all those other damage types". Fire and Cold typically only matter if something is resistant/immune to it, or if we fight Trolls (which happened, and was brutal since out of the whole party, I was the only person with fire damage, outside of using torches and an improvised weapon, because heaven forbid the game allows non-magical fire arrows to exist).
So I'm hoping to make for cool moments where you find out a particular damage type matters more outside of some weird niche thing (like vampire regeneration).
