@tetrasodium I am still waiting on answers and responses to multiple posts. I read an entire separate thread to satisfy you misquoting me, and then it seems you think I was being disingenuous because I did not post my answers in that thread. Now, maybe I'm simply misreading you, but I would like a straight answer, because if you want me to copy and paste everything I wrote into that second thread, that will take me about 10 seconds to do and then we can go back to the discussion.
Also, since we seem to have moved on to critical hits, let us not forget one of the major rules to critical hits in 3.5. They needed to be confirmed. Sure, you might crit on a 12, but then you need to roll a 12 or higher again. 5e does away with that by making the critical simply count.
Also, the only dice that were doubled were the dice from the actual attack. Critical hits state "
Any extra damage dice, such as from a rogue's sneak attack, are not rolled multiple times." So, if 5e made crit-fishing as easy as it was in 3.5, where a 12 crits (which by the way I do believe was both a highly specific build and a high level one) then you would end up with far more powerful blows than what 3.5 provided. (barring of course the feat that allowed you to break this rule, per 3.5 having a feat for every rule to provide exceptions)
But it was just one tool right? Same as the monsters (some of which we've shown to be stronger, and all are certainly more mobile), the negative status effects (spoken about ad nausem), the tactical combat rules that I discussed, the weapon rules I discussed... you know, it is almost like DnD 5e has quite a lot of tools as well.
You want to make a more dangerous Hobgoblin? Take the Hobgoblin captain, give him Mage Slayer and Magic Intiate for Booming Blade.
How about you give an Owlbear Rage and Frenzy?
Take an Orc war party and add an Orc Claw of Luthic who uses Spiritual Weapon, Bless and Cure Wounds to heal the Orc Blade of Ilneval who is commanding the orcs to make additional attacks on the party.
Give some Goblin's Skulker, and put them in a dark warehouse, firing arrows at the party.
Then, add in facing, new flanking rules, change the AO rules, do weapon speeds and Greyhawk Intiative.
If you want more complex challenges, more tactical combat, then just do it. This is not a question of "how many rules do I have to copy directly from 3.5". Take the rules in 5e, use them, alter them just slightly. And you can make devastating encounters.