Classes aren't synonymous with exclusive niches. If we look at classes as instead being packages of abilities that either go well together mechanically or are popular, than ranger makes a lot of sense. A lot of people want a dip in thief skills, good combat ability, and a little healing after the battle. If D&D were a point buy game, a lot of characters would look like rangers, some like fighters and wizards, and very few would look like paladins or bards.
I've been running a number of games in DnD-esque campaigns using point-be systems, mostly in my homebrew but also in other systems. I call these DnD-esque mainly becasue what much of what we played were convertedDnD advenures. I'll try to recall what roles we had. Overall, what most players played were warriors.
Kelandra, run in Steve Jackson's In The Labyrinth game (advanced melee/wizard). This is now around 20 years ago, and we changed over to 2E when the original rules felt constraining, but I will try to recall how it was prior to the change. In the labyrinth was sort of a class system, in that you were either a wizard or not. but was otherwise point bye. We had 2 melee warriors, one ranger-like with stealth and twf, the other more fighter-like with heavier weapons. We had one wizard who worked a lot of illusions. Another wizard was more like a DnD cleric anf focused on heal/buff. We had a dwarf fighter who was very tough but hit poorly. We had yet another fighter who eschewed armor and used a greatsword - lethal but glassjaw. As expected in a system with wizards on one hand and warriors on the other, people were either wizards or warriors.
Another game was in Malleus, an earlier homebrew based on Pendragon mixed Stormbringer (later Elric), WHFB, and Ars Magica. Not pure point-bye, but entirely classless. The system encouraged heavy armor, and we basically had two roles - knight and sorcerer, all characters were a mix of these roles. We had a knight with druid-like nature magic (fighter-druid), a sorceress of air and demons (sorcerer), a honorable knight without magic (cavalier), a champion of law with little magic (paladin), and a sorceress-warrior that was more celtic in feel and used less armor (magus).
The next example was in Dragonstar, a DnD setting in space, run in Action, my homebrew point system. We had a cleric who was also a detective (inquisitor), an elven thief (rogue), a orc martial artist (monk), a human "company man" who tooted guns and became the party face (fighter-bard), and a gadget-style wizard (wizard).
The next was the Shackled City adventure path, run in Mutants & Masterminds. We had a tiger-shapeshifter berserker (barbarian-druid), something similar to a shadowdancer monk (monk), and a big bruiser (fighter). No spellslingers but lots of magical special abilities.
The current game is a long-running Curse of the Crimson Throne, run in Action (the homebrew from above). We have a shapeshifting cat burglar (monk/bard), an elven healer/time mage (cleric), an utility caster (wizard), a lawman/martial artist (monk), and a big bruiser (swashbuckler).
These groups are not completely independent, there is some overlap between players, but represent a sample of a dozen or so people's choices. What strikes me is that almost every character has a bit of magic, often a focused ability like shapechange or a limited teleport. Real spellcasters are somewhat rare, partly because being a spellcaster in a system like Mutants and Masterminds involves a lot of bookeeping.
I mapped the characters to their closest Pathfinder equivalent. I gave each character two "points" to account for multiclassing. This is the spread over classes. Very conventional, if I may say so, similar to what we have at our d20 tables.
bard 2
cavalier 2
cleric 2
druid 1
fighter 4
inquisitor 2
monk 6
paladin 2
rogue 2
shadowdancer 1
Sorcerer 2
swashbuckler 2
wizard 4