The answer to this question is definitely no, rosies are not only slots machines. There are many different variations of slots machines that have rosies as their featured symbol. These variations include video slots, classic slots, and mobile slots.
What makes a rosie a featured symbol on a slot machine is up to the individual developer or manufacturer of the specific machine. However, in general, a rosie is typically a symbol that benefits players by awarding them more wins than any other symbol.
While most rosies are beneficial to players, there are also some that can be harmful. For example, the rosie can be used as part of a multiple-coin payout scheme that awards players more money than they would receive if they only received coins for one coin paid in.
In this situation, the rosie can be seen as a deceptive feature of the slot machine because it does not actually provide any real benefit to the player. As such, it is important for players to be aware of what symbols are featured on a particular slot machine and how they can use them to their advantage.