All the broken systems of DnD (which means quite a lot of them, really) shove their shortcomings right into your face at low levels. It was clearly not designed for this.
What systems exactly are you talking about? I'm not the biggest fan of (A)DnD, but I don't really remember negative system's traits which show themselves in lower level campaigns and absent from higher level ones.
Oh my, don't get me started on analyzing why DnD is inherently broken. When I start with that, it never ends. Also had enough fights with blind fanboys claiming that the system is not broken, when it just objectively is. I don't mind people liking DnD despite knowing and accepting the flaws (we all have our guilty pleasures, right?).
For slightly less thread derailing, I'll just give you one example:
Vancian magic system, which I would find relatively stupid even if correctly implemented, is implemented pretty bad in D&D. It is supposed to cost mages time to prepare spells. So spells are really more rituals than anything else, prepared and then let loose at the correct point. But in D&D, it always takes exactly one full rest to prepare stuff. With sorcerers, blessed souls, warlocks, etc. (all the inherent spellcasters) I can understand that they are exhausted and need to rest. But mages? What do they do in the rest time? Do they get any sleep when preparing? Do mages not need to sleep? Or is preparing spells that easy? If it is that easy, why do they need to rest 8 hours and not just half an hour and could do it any time, using just 30 minutes of resting? Why can I not choose to take less time and prepare less spells? With a first level mage, why the heck does he need all that time to prepare a single colour spray? It really seems like 1st level is supposed to display children.
Also, why can one only prepare X 0 level, Y 1. level, Z 2. level, W 3. level spells, etc.? Why not a simple contingent of spell levels players can use freely? Why not always the same spell contigent (or only slightly growing), while levelling up unlocks to use more potent spells?
Questions, questions, questions, none of which can be answered really well, all of which proving that the whole implementation in DnD is just not believable at all. The sole reason this immersion breaking nonsense exists is balancing. Imagine a level 10 caster having a spell contingent and using it completely for fireballs. How many would that be? 15? More? And when knowing that fire resistant foes come up next day, just switch to 15 ice cones. There you go, doom machine, much earlier than mages normally become that strong. The sole reasons for all the arbitrary restrictions.
The whole magic system is so inherently flawed that it needs such artificial restrictions to be sustainable. When you have at least some experience in game design, you smell when something was done purely out of balancing reasons. And when something is done purely out of balancing reasons, the system in question has a severe design flaw, and should be redone.
In Shadowrun, each caster can theoretically learn & cast any spell in existence (not all of them, you still have to select some). And it works like a charm. Why? Because a lowly street shaman trying to cast something as powerful as a Power Word Kill would most likely never make the spell casting check and then die from not being able to stand the backlash from casting (no matter if successful or not). A powerful and experienced mage on the other hand might attempt to cast it as it is likely enough that he both succeeds in casting and survives the backlash.
Two very easy and intuitive dice rolls is all that is needed to make a working
and believable magic system that is unlimited in what you can do with it (it is really easy to come up with new spells, should the need arise) and scales well for any power level of mages (you can also select how powerful your spell shall be, making the casting harder). Perfect, especially in comparison to the DnD nonsense.
4th edition DnD improved the casting a lot by introducing unlimited, per encounter and per day spells. Unfortunately, it used that system for every single class, so every class in 4th is basically a caster with different spell descriptions, making every class essentially the same. Way to ruin a good idea.
PM me if you want more of that, I won't continue another DnD discussion derailing this thread even more