I rarely use caulking. Most leaks between the toilet and the drain flange will not show up on the bath floor. Some are so slight that they never drip but do slowly rot the wood under the toilet.
One bath had tile floor that was very uneven. Within a few days, the toilet was rocking a bit and repeated tightening helped very little. To avoid breaking the toilet base, nylon wedges were used to make mostly continuous contact with the toilet base all around. Then caulk was used to hide the wedges. The results were quite good.

Here is a link that might be useful: Wedges

If you do caulk, leave the back open. While I agree most leaks are going straight down, a serious leak will show out the back and onto the floor.

The caulk is meant to keep water that is spilt on the bathroom floor (usually children) from going under the toilet and causing water damage to the subfloor or areas below. .Bathroom floors get wet often, and should be waterproofed. I caulk all the baseboard trim in my bathroom also.

The caulk is meant to keep water that is spilt on the bathroom floor (usually children)

==>>> ooohhh... its child related ... but it aint water ... its more about young boys and interpretational aiming ... if you get my drift ...

as noted.. just leave the back open.. unless you have a very inspired young man ... lol ...

i doubt you will find this in any plumbing manual ... lets just say ... i learned from experience ...

ken

Our plumber always left the floor/toilet seam uncaulked, but when we had a major inspection of every nook and crannie of the house for a conversion of the title to condominiums, the inspector wanted those seams caulked. I said, "Yes, SIR!"