pay online my Federal estimate tax payments for 2018?

[LP1968]

Turbotax advised to mail to IRS my  2018 Federal estimate tax payments. 

However, I was informed that https://www.irs.gov/payments/direct-pay allows me to make the 2018 Federal estimate tax payments on-line which seems easier to me. 

Why not pay on-line then instead of mailing the actual check? 

[linear]

Answered in your other post.