I Believe This Is The Cause Of Snowball

It's the high pace of damage.

Conceptually, item leads and level leads increase the ratio of the stats of those ahead compared to the stats of those behind. I believe Runes Reforged lowered a lot of the potential Armor and Magic Resist we had available in the background from our old runes pages. New runes compared to old masteries offered more damage than before. Tank items offer less stats compared to before. In summary, damage is higher.

When damage is higher and defenses are lower on average, item leads and level leads lead to a relatively massive ability to rapidly kill someone compared to before. When resists where higher and access to damage was lower, the same item and level lead would allow for faster kills as well, but there was counterplay available. There is no counterplay when a player has access to using his item and level lead to instantly kill. In the old days, I remember losing lane or playing poorly in jungle, and I would be forced to beacon to base to heal. I would beacon many times in losing games, as it was me tucking my tail behind my legs and resetting. In today's meta, I can't even live long enough to choose to beacon to base.

Beaconing to base offers no gold and is not a direct snowball mechanic. Dying offers gold to the snowballed killer, and is a direct snowballing mechanic.

If you were to reduce damage somehow, possibly by expanding defensive mini-runes or offering great, defensive runes and better items, while possibly lowering damage in runes at the same time, It would be a step in attempting the older times to kill. The current time to kill is what's causing the snowball, because it confirms kills. That kill confirm just adds to the snowball. In the past, that big burst that didn't kill you lead to possibly a beacon, which isn't a snowball mechanic.

There are other benefits to lower times to kill, including tank stats helping you actually survive a rotation of damage, lifesteal builds allowing for drain tank fun, assassins having to meticulously get in and out repeatedly to do their work, adc's actually doing sustained damage instead of burst damage (this would be the perception when damage is lowered), and CC chains actually being valuable as a duration of CC leading to kill confirms rather than a blip of CC preceding a 1-shot kill.

I just miss the old feel of the game, and I promise you that lower damage would reduce the score spreads we see in these stomps we've had for the past 2 years.