It is necessary for boys to propose marriage, because it can reflect the sincerity of boys to marry girls. Maybe two people have just entered the society together and don't have much savings, but sincerity and respect are very important. The girl will be very moved and express her sincerity by proposing marriage.
The marriage proposal ceremony is also very necessary for girls, which is also a respect for girls, because many girls are very much looking forward to their beloved boys proposing to them.
Although there is no mandatory requirement to propose, if you love that girl, you still choose to have a proposal ceremony. Even if it is a simple proposal ceremony, as long as the boy really puts his heart into it, the girl will be moved, and this process will be treasured in her memory.