toucanbuzz
No rule is inviolate
I'll make the case it's all there. The Buff Caster is a more advanced concept now, requiring some effort. I'd hazard a guess most players like to roll a lot of dice and see their enemies swept before them like chaff in the wind. That's easy: pick damage spells and blast away. But for the Buffer, it's now about the spell list, selecting a balance of Concentration spells (1 at a time, the most powerful buffs like haste and bless), buff spells that don't require Concentration (e.g. aid, death ward, freedom of movement, mage armor, sanctuary, warding bond), ancillary buff spells (e.g. guiding bolt), and situational buffs (e.g. darkvision). It's also about class features that complement the buff, such as a Bard's song or the Sorcerer ability to Twin buff spells. Further, there's an art about deciding which spell slot in which to cast the spell (do you need your Bless to hit 4 people instead of 3). This requires individual scouring of the spells and planning ahead. The same would apply to a Control caster, and from actual game play, I personally believe the Control caster that sets the battlefield rather than cause damage is probably one of the stronger characters.
Special Maneuvers are there, subject to DM approval as optional rules. This allows D&D to be attractive to new players, who may desire simplicity to start, and veterans who want more options. You'll need the Dungeon Master's Guide for things like:
(1) Climbing onto bigger creatures; (2) Disarming; (3) Mark an opponent; (4) Overrun to push through a space, (5) Shove aside or off that cliff; (6) Tumble through a space. (DMG p271-72).
This blog post seems to have an accurate link to the basic optional rules (no Xanathar Guide).
A few points, given I've been blessed by a good core group of gamers who come to my home to play. One of our gamers runs Dungeon Crawl Classics games (the AL and PFS version) at the game store, which means he has to invite anyone who sits at the table. In return, DCC provides adventures for him to run and the store gives him a table. He will get bad players, he will get unimaginative players, and he'll get folks who simply don't want to spend time making a character and instead want to get right to the action. I don't think it's the game system; it's the personality and play style of the gamer. When I attended the D&D opening at GenCon, I had a limited time to play and wanted to get straight to the adventure. I was more than willing to play the prefab Mike the Generic Fighter to get to the story, and the Generic Fighter ended up being the rallying cry for the table in his quest to become a council member someday in Phlan, rewarding his pals who got him there (after his last village was buried by a volcano). The player who spent an hour making his own dual-wield Drow Paladin had no story (he's a drow, don't ya know!) and was boring.
Nevertheless, the moral of the story is that D&D is no different than anything else. Some players have fun spending the hour(s) making the complex character, and others don't. Over time, we'll gravitate to long-term groups that are on the same page. (And, we all know that telling the other person they need to spend more time (or less time) making a character never goes over well, and I in no way at all want to make this a critique of player choices to spend more time making complex characters.) As long as you've found an avenue to have fun, it's all good. AL and PFS don't get this long-term group experience, such as sitting down in a Session 0 to make characters as a group and the ability of experienced players and, if needed, the DM to assist with suggestions to achieve a concept (e.g. I want to build a sniper or I want a pet or to summon things).
D&D gives DMs something to fall back on. There's no guarantee, however, that a DM does their homework in any game system. Understand the frustration that one wooden door is DC13 in one game and DC17 in another (maybe better wood, or warped shut by water?). But note, even Pathfinder can't make a table for every possibility. There's going to come a time the not-so-super DM in any game is going to have to fall back on their guided common sense. In D&D, the entire goal of its guidance is to avoid pausing the game to consult a table to see if climbing a chandelier rope is different in DC than a rocky wall with handholds. Instead, DMs are to use the ranges of "very easy, what's the point (DC5)" to "near impossible, you'd better be a rogue (DC30)" ranges as others have referenced, modifying slightly if that door is warped or rotted.
Merric gives some great play advice for D&D DMs and setting skill checks. If you've got a good open relationship with your DM (I know, hard in informal AL play), I'd pass it on.
