You can stack snow covers up to a full block beside a cactus without breaking it

When you stack snow covers on top of each other beside a cactus, the cactus will stay there. This issue always occurs.
What I expected to happen was...:
After stacking up the snow covers to a full block the cactus should have been destroyed like if you would place a block beside it.
What actually happened was...:
The cactus stayed beside the staced snow covers.
Steps to Reproduce:
1. Find a cactus.
2. stack up 8+ snow covers right beside it.
3. The cactus is still standing