Well Might Guy and Lee I think are exceptions to what you just stated. And Might Guy was relatively top tier.
It depends on what you consider top tier. I for one, do not actually consider Lee and Guy top tier. Guy is strong, sure. I would call him low kage level probably stronger than hokage Kakashi, but weaker than Tsunade (though I would accept arguments about that). However, I don't really consider this to be top tier (and I don't count suicide techniques as a part of a character's regular power level since they can only use it once and then die, so his power in the 8th gate doesn't count). As for Lee, I consider him to be weaker than Guy since we don't know whether he can use the 7th gate, and more importantly, he has yet to show any techniques like those ninjutsu-imitation taijutsu techniques that Guy uses in the gates such as morning peacock or afternoon tiger.
For me, when I think of the top tier, I'm thinking of characters more along the lines of:
Naruto (from bijuu mode onwards)
Sasuke (from EMS onwards)
Madara (from EMS onwards)
Obito (from MS onwards)
Hashirama
etc...
Notice that all of the above characters have/had either some powerful bloodline trait, was a transmigrant or a jinchuuriki (and actually all of these characters fit into multiple of the categories that I just mentioned).
Now, there are a few shinobi who don't have a powerful bloodline trait, transmigrated chakara, bijuu chakara or anything of the sort that are at least close to the level of the characters above.
Minato comes to mind.
Then there are others that don't have the aforementioned advantages who are genuinely strong compared to most shinobi, but would get absolutely fodderized by the top tiers.
Sakura is an example of this. I honestly would consider her to have surpassed Tsunade. However, being able to punch the ground really hard is no match for the likes of rinnegan abilities/kamui/amaterasu/perfect susanoo/bijuudama nukes/truth seeking balls/wood style true several thousand hands/etc...
The problem with the way power is written in this series is that most shinobi are only allowed to have one main gimmick (which is usually very limited), while the top tiers are either able to build up very versatile arsenals of techniques or an overwhelming amount of raw power.
For example, Sakura's arsenal can be summed up as punch and healing. I know that this might be a bit of an oversimplification and it may sound like a bit of a downplay, but let's compare this to Sasuke's arsenal:
Several changes in chakara nature (all 5 in fact), with Sasuke having demonstrated high levels of proficiency in fire and lightning style jutsus. These jutsus cover various ranges. They vary in destructive capacity. They can be used both offensively and defensively. Etc...
Then of course, genjutsu is an option for him as well. This can be used to show people illusions, control people, look into people's memories or extract information, paralyze people instantly and knock them out. Heck, some genjutsu can even just flat out kill people.
Then of course, Sasuke can also copy ninjutsu.
He has precognition.
He can incinerate someone with a glance via amaterasu.
He can shroud himself in a giant flying tengu warrior that can act as an ultimate offense and defense (susanoo).
(Before he lost the rinnegan)
He could teleport himself and other people/things within his vicinity (without even touching or looking at them).
He could make portals and traverse dimensions.
He could absorb chakara.
He could use a coreless chibaku tensei.
Etc...
Sasuke got all of that, while shinobi like Sakura just get punch and healing. Lee only gets taijutsu, which is limited because if there is an opponent that Lee can't or shouldn't touch (e.g. maybe they are coated with lava or some toxic to touch substance or maybe they have kamui-like intangibility or something like that), then Lee is out of options. Shikamaru's shadows are limited. Ino's mind body techniques have certain drawbacks. Etc...
The suckish part is the fact that some of these other shinobi should technically be able to expand their arsenals, but Kishi just never let them. For example, Sakura should at least be able to learn an element or two and some genjutsu since she was originally supposed to be a genjutsu type. Shikamaru's shadows already use yin release, so what is stopping Shikamaru from learning some genjutsu on the side, and maybe an extra element?
Heck, Tenten could become a master of seals and spacetime ninjutsu.
However, Kishi doesn't let anyone besides the characters with inborn advantages even try to do such things, while he allows shinobi like Sasuke to expand their arsenals into areas that don't even stem from their in born traits!
It's basically the classic trope of the rich get richer.