When Picard is taken prisoner by Cardassians he and his group has a hockey puck size shield emitter for blocking a corridor so they can escape. If that isn’t phaser resistant it would be useless. Same for the larger shield emitter used in Insurrection to block the cave. I believe in The Siege of AR-558 they experience supply shortages due to the intensity and length of combat. If they had personal shield emitters, either for the body or puck style area shields, they could have already been depleted by the time the episode begins. By the time of DIS we might assume the defense-offense balance to have swung to offense in the realm of small arms. Or, we might consider organizations still provide only basic equipment to shipboard combatants the same as they always have. In TOS we see the Gorn have a phaser sniper rifle, and Starfleet has a photon grenade mortar. In a movie security personnel get ballistic shields, but we never saw anything like that for red shirts in TOS. In TNG and DS9 combat robots exist. In DS9 soldiers get that inch thick foam rubber jacket which might be phaser resistant and we know crates in TNG and DS9 can resist normal kill shots. In DS9, when they talk about enacting military law that’s when they also talk about distributing personal shields and photon grenades. All together, that means we don’t see better equipment in DIS because they aren’t at war. Alternatively, we are seeing improved defenses and don’t know it. Season 3 episode 1, people vaporize when hit by the donut guns. Later episodes they just die from wounds. Later we see one more person vaporize. What if the people who don’t vaporize have phaser resistant clothes. On its own it’s not that useful, but if you quickly get help a doctor might save your life. Sure, even in TNG they should have personal shields all the time, and DIS Season 3 should give everyone SPARTAN armor which grows from their tricomms, but they don’t. In TNG a combination of budget and story restriction probably stayed their hand. They wouldn’t want to write battles around people with defenses, they rather they Matrix dodge the phaser aim-bots.