I agree that a doctor who has already performed the procedure or surgery is better than one who has merely read about it, and that there's a difference between reading about love, and being in love.

Clearly every doctor at some stage in their life must have performed a procedure for the first time, and if Elizabeth is going to fall in love then she will have to do it for the first time. Preparation beforehand where you learn from others is useful in those cases. A trainee doctor studies anatomy from textbooks and from cadavers, Elizabeth may study love from philosophers and novels (the improvement of her mind by extensive reading - chpt 8). A trainee doctor observes experienced doctors performing the procedure, Elizabeth can observe her parents' and others' marriages (Had Elizabeth's opinion been all drawn from her own family, she could not have formed a very pleasing picture of conjugal felicity or domestic comfort. - chpt 42). A doctor performing the procedure for the first time may be surprised by say how much pressure it takes to push a scalpel through skin, but have a good idea of what the heart is from anatomy lessons, Elizabeth may well also have much to learn from actually experiencing love in the first place, but know somewhat of its complexities and facets. It makes sense for a trainee doctor to learn before first performing a procedure due to the risk to a patients' life if it's performed wrong, it makes sense for Elizabeth to know about love due to the risk to her happiness if she gets it wrong (especially given divorce laws of the time).