Fruits do not assist in the fertilization of flowers. Fruits are produced by plants after the flowers have been fertilized and this has resulted in the creation of seeds.
Plants use nectar, attractive colors, fragrances and other chemicals to attract animals to fertilize their flowers. Fruits are not used for this cause.
Plants need to ensure that the seeds produced by the parent do not fall around it as that increases competition for the limited resources available for the plants. If the seeds can be carried far away from the parent tree there is a higher possibility of the seeds germinating and the offspring surviving. To accomplish this fruit are produced; these are eaten by animals that use most of the fruit as a source of nutrition. The seeds that are in a protective coating are not digested and fall with animal excreta far away from the parent plant. The young plants do not have any competition from the parent plants and the excreta that they fall out with also has nutrients that are used by them in their growth.
Likely the main way that fruit helps in the fertilization of flowers is the fact that fruit trees and their blossoms require fertilization as well so they both work to attract the help of bees and other insects to facilitate that. In large fruit-growing operations huge amounts of bees are often brought into the area to be sure that the pollination takes place so anything in the area is also likely to benefit just as fruit growers benefit from having large grasslands or forests nearby to help supply insect-labor for the pollination process. There are worries about this process as massive monocultures have led to non-standard practices that may not be viable in the long term.