germinating them and growing them indoors for a while allows the plants to grow stable roots so they can withstand it better when they are transferred. you can plant them straight into soil outdoors but for the first few weeks your gonna have to spend A LOT of time at the grow spot to ensure that your plants will survive, making sure they are getting enough water and sunlight, but not too much, seedlings seem to die fairly easily in hot and dry weather. as well with too much water, very extremely fragile in this state.

it can be done, don't get me wrong but if you want all of your plants to survive you may have to give them a little help. (especially if its bag seed in this case you don't know how its going to grow or act under certain conditions)

(remember this, it all depends on where the plant originates from, for example if the strain you choose was grown in mexico it will have some difficulty growing in canada. If you breed the strain it will be able to handle the conditions better in the next generation)