@Demyanenko_square_jaw I think you've overlooking a number of things stepovers provide apart from what has already been mentioned. There's an issue with the stepover where you have players who do them for seemingly little reason, as opposed to others who can do many in a row with each one serving as functional because of what it provides.
@Gio pointed out Ronaldo's usage and the benefits it provided him, but the problem with Ronaldo is he was an outlier and a freak, so what he could do was, or is not really a template for other players to follow. It wasn't just dribbling ability opponents had to process with any dribble Ronaldo made, it was also his explosive second actions and the fact he was already outright faster than them in any scenario anyway - defenders are going to have half their mind overloaded with thoughts about that, let alone the stepovers coming towards them. Actually, if we remove pre-injury Ronaldo, we get a very clear picture of the benefits of the move when not backed up by extraordinary physical attributes.
For a normal player, (or, let's at least use ones who are not top of the top percentile, like Ronaldo) the stepover can place them in a battle of wits and reactions with an opponent. Like with a punch feint in boxing, or a kick feint in Taekwondo, or the combination of either in MMA etc. an opponent has to decipher what the real intent is behind each individually actioned feint, which, in this case is the stepover off either the left or right foot. Just as with a feinted act of aggression in a combat sense, the body and the mind are going to react and prepare for each unique action in a sequence because response time is essential for the actual follow through, be it a block or dodge or counter strike of your own in a combat sense, or a body shaped correctly to even be in a position to tackle, in a football sense.
With each stepover: left to right, right to left, the defender has to shift his bodyweight and his own centre of gravity as well as place his feet correctly lest he become rooted to the spot - if done correctly, this practically always leads to the defender doing a dance of sorts where his coordination is offset and he's moving off-time with each independent stepover.
When a great exponent of stepovers approaches a defender ill-equipped to process the action, the defender will often appear to be frozen in place, motionless and hypnotised, most of the time, that will occur because his brain is in a lagged state, very probably processing the stepover
before the stepover being seen in real time. The player executing the stepovers then has an easy stroll past said player and it's not infrequent to see the beaten defender either fall flat, like some kind of sleeping cow being tipped in a field, or just stand still for the entirety of the move past him, like a mannequin. The stepover has not only done its job, then, it has also programmed that player to fear one-on-ones with the exponent, which is where the likelihood of fouls and cards enter the fray in future encounters, not to mention frustration and further loss of concentration.
This leads on to the second reason stepovers can be so useful for those proficient with them - they buy the player
and his team time and they disrupt the opposing teams defensive schematic. Of course, being humiliated and bamboozled is not something any defender wantonly seeks out, so in the next scenario where he is isolated with the same player, he is going to try and hold position and not get duped once again, in the meantime, this statuesque defender has effectively removed himself from the game. His concentration is now compromised because all he's thinking about is the player with the ball and not the things happening around him and he's moving half a second slower because he's overthinking things instead of reacting instinctively and intuitively as he normally would, he very probably also needs assistance from another team-mate, which means two men have been drawn to one man and are no longer watching what his team-mates are doing or the spaces they're now running into.
Players who are smart and are doing the stepovers whilst being acutely aware of their surroundings and the opportunities it can provide are like gold dust, however. It's not uncommon to find that great dribbling goes hand-in-hand with selfish or self-involved end-product (i.e. the 'hero run' a lot of dribblers make), which is where the move, and sometimes not the player, get admonished. It's the player who makes a potential golden opportunity he's just created for himself or a team-mate, 'pointless', just as it's the good players who make the exact same scenario a huge problem for the opposition. There's a big difference between a Denilson doing endless stepovers and a player like Ronaldinho. Even young Cristiano was basically learning his trade and the countless ways he could incorporate those 'show pony' stepovers into his overall play to the benefit of himself (heh) or his team.
Anyway, yeah. Stepovers.