Is it:
Corruption
I was there when kings were born
Corruption has always been there since the start of mankind
Yet all avoided me lest they know my scorn
Corruption can lead to serious consequences
The strongest fell in my presence
The strongest Empires/Dynasties fell because there was corruption everywhere, even within the king's palace
Consequences ignored in my absence
Nothing to ignore when there's no corruption :)
Some have reached out and felt me
Bribery? Some have felt the effects of bribing someone succesfully
But none have ever touched me
You can't touch corruption, cant you?
OR
You are:
Death
I was there when kings were born
Duh!
Yet all avoided me lest they know my scorn
Who wants to die?
The strongest fell in my presence
The wealthiest, strongest, most powerful, all will eventually die
Consequences ignored in my absence
No death, nothing to worry about!
Some have reached out and felt me
Dead people
But none have ever touched me
You can't touch death, can't you?