Why can’t I collect lower level bouquets in The Floral Frenzy?

The Floral Frenzy Event incentivizes you to collect the maximum amount of points possible and create as many Level 10 bouquets as you can for the duration of the event!

Points are collected as soon as you create new levels of bouquets by merging Leaves together. When you manage to create the final level Celebration Bouquet, you receive 10 points for creating it and then you can tap to collect it in order to add another 20 points to your total.