I've built a number of serverless systems over the past few years on AWS and GCP. None were too extreme, but ranged from moderately complex SPA to silly chat bot. Some saw light, but real, usage.
To echo what others have already said: the lock in isn't in the compute, it's in the ecosystem, which also happens to be where all of the value is.
Like everything else in our industry, serverless is a series of trade offs. There are a number of classes of problems where it is absolutely worth trading the downsides of serverless for the agility and velocity the ecosystem can provide you. As with anything, the key is knowing when it is the right tool and how to use it properly.
To echo what others have already said: the lock in isn't in the compute, it's in the ecosystem, which also happens to be where all of the value is.
Like everything else in our industry, serverless is a series of trade offs. There are a number of classes of problems where it is absolutely worth trading the downsides of serverless for the agility and velocity the ecosystem can provide you. As with anything, the key is knowing when it is the right tool and how to use it properly.