The failure mode is worse than the absence. A chatbot that cannot answer, that loops, or that stands between somebody and a person is a barrier at exactly the moment somebody was willing to make contact. Visitors who encounter one and cannot get through frequently leave rather than persisting, and you never learn it happened. For a business whose enquiry volume is small, losing one that way costs more than any efficiency gained.
Where it does earn its place is specific. High volume of repetitive questions with definite answers, such as hours, location, whether you carry something, or the status of an order. Coverage outside working hours where the alternative is silence. Or qualification, where a few questions route somebody to the right place before a person is involved. Those are real and none of them describe a business with twenty enquiries a month.
The cheaper alternative that solves most of it is a well built page answering your most common questions, linked prominently. It handles the same repetitive queries, costs nothing to run, requires no configuration, and has the additional benefit of being findable in search, which a chatbot conversation is not.
If you do add one, make escaping to a human immediate and obvious rather than buried after several attempts. The measure of a good implementation for a small business is how quickly somebody who needs a person gets one, not how many conversations were handled without escalation.
There is a newer consideration worth stating. Tools generating answers from your own content can now produce fluent responses that are confidently wrong, including about your prices, your availability, and what you offer. A wrong answer given in your name is a commitment somebody may reasonably rely on, and constraining what it may say matters more than how well it converses.
If you do run one, read the transcripts weekly for the first month rather than only the volume. What people actually type reveals both the questions your site fails to answer and the moments where the automated reply frustrated somebody, and both are more useful than any completion metric. Most businesses install one and never read a conversation, which means they learn nothing from the thing they installed to learn from.