Gamerule commands allow parameters other than true/false

When issuing a gamerule command, for example:
/gamerule doFireTick on, the game will accept that "on" parameter without throwing any errors.

This can result into major confusion, since the game will parse anything other than "true" as false.

Expected

• Throw an error for an incorrect paramter

What happens

• The game accepts the faulty parameter, yet considers it as false

To reproduce
1. Change a gamerule to anything other than "true/false"
2. Check the gamerule, it will say the exact parameter that was entered
3. Notice that it will be considered as false