If you’re growing cannabis from seeds, you’re only doing it for fun, not because you’re intending to produce buds more cheaply than buying it from someone. With seeds you will have plants exhibiting many different characteristics, while all being from the same breeding.
Think of it like a couple of humans who have twelve children. Of those twelve kids - all raised in the same environment by the two successful parents - you’ll have 12 distinct personalities. One kid will be a doctor, another a lawyer, still another an ameteur boxer, while another will die in a drunk driving accident, another will be divorced six times with four kids not in her custody, etc. In agriculture this is referred to as a specific plant’s phenotype. If you are at all serious about growing cannabis you should grow strain that has been carefully phenotype selected for good characteristics, such as: resistance to pests, excellent yield, high THC content and most importantly a terpene profile that is appealing to that individual.
None of these characteristics is identical amongst perhaps twenty cannabis plants raised from seeds procured from the same breeding.
Acquiring clones from a reliable grower is a simpler method for a beginner - it’s rather easy to acquire a well bred and selected plant - and you can clone this plant over and over and have the exact same characteristics to repeat while you’re learning to perfect your growing style.
Additionally, growing cannabis from seeds means that half of your seeds are going to be male - and half are female. Unless you have control of your lighting cycle you’re not going to be able to see which are which and you’re going to work twice as hard to raise these plants because eventually you’re going to see which are male and which are female (after months.) When you cull the males to ensure that they do not pollinate your females so you get the best, seedless yield possible it will be with a sense of regret as you spent a lot of time and effort taking care of ALL your plants - and half that effort is for naught.
You could purchase feminized seeds - but then you’re looking at the same issue with phenotyping again.