Why is the match timer so bloody short

I just had a match where I dropped down to 26 health because RNG wasn't in my favor (start indicated Noble was the way to go, just to have everyone else go for the same type of idea). Finally get that 6-Noble setup going with a Braum/Ashe in addition. Ready to rumble, right?

NOPE.

Two rounds later I'm dead. How am I dead, you'd ask. Noble/Guardian should be powerful, right? An endgame setup. Well yes, it is. But then you need to remember others also went for similar tank setups. What happens instead is that the first match had both of us have 7 units surviving until the timer ran out and I lost ~24 health. The second match the guy had an Ashe with ~25% health remaining while I still had my entire board active but alas, the incredibly short timer ran out again so there goes my remaining health. Goodbye LP despite not actually losing; thank god I basically have nothing to lose yet since I just started.

Brilliant. Design.

If you make balance around having tanky comps, e.g. Noble/Guardian, then why make the timer short enough that they literally lose by war of attrition? Just have the match last until the very end. If it's not ending, maybe you screwed up balancing and shouldn't just kill off both players for the sake of "speeding up the game"?