is this why most of what I've read has recommended heavy, sharp or refined infusions, and raw early game? Many of the others are just not worth it?
Raw is fantastic for early game and non-Strength/Dexterity builds. Sharp and Heavy are strong in PvE and low level PvP. Refined is the best infusion in the game for higher levels.
Fire is useful early game on a secondary weapon because many enemies will writhe in agony when hit by fire damage. Deep is OK. My main issue with Fire and Deep is they just feel unnecessary. They're elemental versions of Raw, which can already be buffed with elements. They don't really add anything to the game.
Lightning, Dark, Chaos, and Crystal are fine in PvE, underpowered in PvP. They fill in the necessary role of weapons that deal damage scaling on casting stats. I'm using a Lightning Dragonslayer's Axe on my current Faith build and it kicks bosses' asses because they're almost all weak to Lightning. Unfortunately, in PvP split damage is generally not great and these Infusions can't be buffed with spells or resin.
Hollow is good IIRC. It's pure physical damage, can be buffed, and is sorely needed when there's only one natural Luck scaling weapon.
Simple and Blessed are basically pointless for anything but dedicated parrying tools (where they don't hurt the effectiveness). Their damage is awful and they regenerate FP/HP incredibly slowly.
Blood is outclassed by anything that can take Carthus Rouge. Poison is utterly worthless.