Is the Sync Button Cheating?
Sync matches two tempos. That is the whole function.
Almost every beginner asks this, and almost nobody asks it out loud. They ask it quietly, usually after reading a comment thread where somebody with an anonymous avatar made them feel like a fraud for pressing a button.
The short answer is no.
The longer answer is more useful, because the question underneath it is not really about sync. It is about whether you are allowed to call yourself a DJ yet.
What sync actually does
Sync matches the tempo of one track to another. That is the entire function.
It does not pick the track. It does not know whether the track is any good, whether it fits what is playing, or whether the room will respond to it. It does not know where the phrase starts, so it will happily lock two tracks together perfectly in time and completely out of musical alignment. It does not decide when to bring the new track in, how long to blend, what to cut, what to let through, or when to get out.
It does one job out of roughly fifteen, and it is the one job a machine is genuinely better at than a person.
Where the argument actually comes from
It helps to know why people feel strongly, because they are not being stupid.
For most of the history of DJing, matching two records by ear was the gate. It took months to learn and it was the thing separating people who could do this from people who could not. If you could not beatmatch, you could not play, full stop. A generation of DJs spent a long time acquiring a skill that a button later made optional.
That is a real thing to feel some way about. It is not the same as it being an argument about whether your mixes are any good.
Why you should still learn to beatmatch by ear
Here is where most of the "sync is fine" crowd stops too early. You should learn it. Just not for the reason you have been given.
Not because it makes you authentic. Because of four practical things.
Sync is not always available. Walk into a venue and you may find decks that are not linked to each other. No link, no sync. If that is the first time you have ever matched two tracks by hand, it is a bad moment to find out.
Sync is only as good as the analysis. It relies on the software having correctly worked out the grid. On a clean modern club track that is usually fine. On an older record, something with live drums, a track that speeds up and slows down because a human played it, the grid is often wrong and sync will confidently lock you to the wrong thing.
You have to be able to hear it drifting anyway. Whether you pressed sync or not, you need to notice the moment two tracks start pulling apart. That is an ear skill, and the only way to build it is to spend time listening to two tracks fight each other and nudging them back.
It trains everything else. The listening you do while beatmatching is the same listening you use for phrasing, for EQ, for knowing when a transition has gone on too long. People who skip it tend to have a blind spot that shows up everywhere else.
So: use sync. Learn to beatmatch anyway. Those two things were never in conflict.
What actually separates a good DJ from a bad one
Think about the last set you heard that genuinely moved a room.
What made it work was the choice of records, and the order they came in. It was the DJ noticing the room was flagging and reaching for something with more weight. It was the transition that arrived exactly where the phrase turned over. It was knowing when not to mix, and letting a track land on its own.
None of that is tempo matching. All of it is taste, attention and judgement, and none of it has a button.
Nobody on a dancefloor in the history of dancefloors has turned to a friend and asked whether that was synced.
The honest position
Use the tools. All of them. Then spend your practice time on the things the tools cannot do for you, which is most of them.
If someone tells you the sync button is cheating, the useful follow-up question is what they think the job actually is. The answers you get back will tell you fairly quickly whether they have ever had to hold a room together.
The only real test of whether a mix works is whether it works. Nobody listening back can tell you what you pressed, and nobody cares. Record one and send it over.