Blizzard could easily solve the leaver problem by adding something to Competitive that already exists in other modes - backfill.
Not every leaver does so deliberately.
There are many reasons that can cause someone to unintentionally disconnect from a game - Internet service interruptions, power outages, unexpected hardware failures, & more.
It’s already unfair that Blizzard punishes those who disconnect due to reasons beyond their control.
Increasing the penalty is not the solution.
I play on console where accounts are free to make and I still say that increasing the leaver penalty is not the solution.
Backfill is.