Companies attract new customers in several different ways. Each of these has a cost. They can buy expensive advertising, for example. Or they can have a sale where the items temporarily cost less. Interest-free loans are just another one of these tools to get you to buy an item you otherwise wouldn't.
Unlike, say, watching an ad, it's possible that paying a lower price or getting an interest-free loan has some benefit to you, but if you get that benefit only by buying something you shouldn't have, then overall the exchange is not beneficial to you.
So, imagine you want to buy a table. You see one you like for $1000 and other you like for $2000 but you can make 4 interest-free payments of $500 for that one, so you don't need the whole price right now. Assuming the tables are of equal quality and worth the same to you, clearly buying the second one is not your best choice. On the other hand, if you find two tables you like equally for the same price, and one comes with an interest-free loan option and the other doesn't, then using that loan is beneficial to you because you can do something else with some of your money for a while, and didn't pay extra to get that.
If you want the table (or car or whatever) no matter what and the issue is only "should I pay the whole thing now or use their scheme?" then yes, there are some things to look into. Some of these places are very sneaky and try to trick you into paying a high interest. They may be unclear about when the payment dates are, and if you're late you owe a large amount of interest from the beginning of the loan. They may charge service fees each month which are technically not interest. And so on. Depending on where you live, laws may protect you from some of this. At a minimum you must read the terms and conditions very carefully.
If you're only going to save (or earn elsewhere on the money you don't have to spend right away) 5 or 10 dollars, it's probably not worth the careful reading and other mental work involved in not being ripped off: just buy the item. But if it's a 3-year car loan, take the time to read it all. There's every possibility the company is simply spending money to get customers, and this can be to your benefit if the product is valuable to you.