Visa Exempt Bali Stamp: One Passport Page Needed?

Hello

I am going to Bali and running low on passport pages.

I am lucky enough to be part of the 45 countries that from June 2015, don't need a visa to enter Bali and receive a visa exempt stamp valid for 30 days.

I read on several websites that you still need ONE EMPTY PAGE for STAMP or VISA STICKER

" Make sure your passport has at least one empty page for the stamp (or sticker)"

http://www.baliguide.com/bali-info/visa_regulations.html

"

• Keep a page on passport empty for stamp or visa sticker!"

http://www.bali.com/visa-indonesia-entry-requirements-bali.html

It makes sense for the visa sticker that actually takes a whole page, but why also for a simple stamp?

Thank you