fearsomepirate wrote:5e dragons have some version of everything else you mentioned.
No, no they don't.
In 5e, damage reduction (subtract a flat amount) has been replaced with damage resistance (half damage) and damage immunity (negate damage). But that doesn't even matter, because not even ancient dragons have either when it comes to weapon attacks. Dragons are immune to the damage type associated with their color and that's it.
In 5e, the highest AC any dragon has is 22. That's one higher than the level 10 fighter I posted. Yes, the CR 24 red dragon is within an RNG of the CR 1/8th who-gives-a-shit.
In 5e, dragon speed ranges from 60ft to 80ft. 3.5 dragon speed ranges from 100ft to 200ft.
In 5e, dragons have a frightful presence that caps out at 120ft. 3.5 dragons have a frightful presence that starts at 150ft and caps at 360ft.
So that ancient red dragon I mentioned? It has 546 HP, 22 AC, and can't do shit to anyone outside of 120ft - not even spook them. If you can use a longbow, you have a range of 150ft, and a range of 600ft when attacking with disadvantage.
So let's compare:
5e: An ancient red dragon (CR 24, 546 HP, 22 AC, 80ft, 160ft dashing) is closing on a mass of archers as fast as it possibly can. We'll use the scout (CR 1/2th, two longbow attacks, +4 to hit, 1d8+2 damage, 150ft range, 600ft range with disadvantage). The scouts get two rounds of attacking with disadvantage and one round of attacking without it before they are in range of anything the dragon can do. 2*2*.15*.15*6.5 + 1*2*.15*6.5 = 2.535 damage per scout. It takes 215 CR 1/2 scouts to murder the CR 24 ancient red dragon before it can put them in range of their attacks. Notice that almost all of the damage is actually coming from the final round (no disadvantage), so if you want to one round the dragon as soon as it shows itself it only takes slightly more.
3.5: A red wyrm (CR 24, 610 HP, AC 42, damage reduction 20/magic, 200ft, 400ft double move) is closing on a mas of archers as fast as it possibly can. We'll use the elf warrior, and even upgrade the bow to a composite one (CR 1/2th, one longbow attack, +3 to hit, 1d8+1 damage, 100ft, 10 increments). The elves get two rounds of attacking before they are within the fear aura (at which point 95% of them stop fighting) and then one final round of attacking before they are in range of the breath weapon (which we'll call a loss). You'll note that the archers can only ever deal damage on a crit (double twenties), and if you checked the math you'd find that the average damage for one of their crits is .4105. That's 2*.05*.05*.4105 + 1*.05*.05*.4105*.05 = .0021 damage per archer. It takes 290,000 archers to murder the CR 24 red wyrm before it can put them in range of its breath weapon.