when would you even need a message queue for something super basic, like, is it ever too much for simple stuff

hey everyone, i've been seeing message queues pop up in a lot of system designs lately, even for what seem like pretty straightforward background tasks. i get their power for decoupling and handling spikes, but i'm wondering about the tipping point. for example, if i just need to send a single email after a user signs up, is setting up RabbitMQ or Kafka really the best first step? or are there simpler alternatives for these simpler use cases? what are your thoughts on when a queue adds more complexity than it solves