Ovulation tests - especially the dip ones with two lines rather than the smiley/flashing faces ones - are excellent at identifying a luteinising hormone peak. What they can’t do is then guarantee that you ovulate 24 hours later, as some women will have anovulatory cycles (an egg isn’t released).
However, the vast majority of women will go on to release an egg afterwards and so on that respect, for the majority of women, they are an important and useful tool for identifying the one or two days of the cycle where you are at your most fertile.
The tests are also a lifesaver for those who have been TTC a while meaning that sex ‘every other day for three weeks’ simply isn’t possible any more.
They are also very useful for those with older partners or partners who have sperm issues, who should only be ejaculating every 72-96 hours as again it helps pinpoint when to have sex with the greatest chance of success.
Finally, they are also useful for those women who assumed they ovulated on a standard 14dpo, only to find out that in fact they ovulate on day 12 or day 16 (or so on), meaning they had either been stopping having sex too early or starting having sex too late in the cycle.
I think your Gynae was wrong to say that without explaining the above.