Some hosts properties are suitable for children and if they wish to welcome under 2's for free that should be a personal choice not one foisted on every host and certainly not on those of us whose properties are neither designed to accomadate children nor safe for them. Airbnb do not own my property nor contribute to its maintenance nor pay for linens nor insure my property - so who are they to dictate to me that I should accept the terrible two's free of charge and put my property at risk, negate my insurance and accept others children for free.
Others have rightly stated here that a blanket policy all children 0-2 are free will likely lead to parents stating that 3 yr olds are two years olds and try to get away with that. Likewise if 0-2's do not qualify in the 'maximum' occupancy, there is nothing standing in the way of say two parents with an infant and 2 year old twins taking your property way above it's maximum. My insurance policy specifically covers me for my maximum '4' guests - not 5, 6 etc. So the child is not insured and infact any claim where 5 guests stayed would negate any claim through my insurance company.
Further airbnb's host guarantee policy, specifically states it does not apply to artworks and other works of art etc - my property is designed for adults and has high quality furnitures, soft furnishings, linens and quality artworks - which is a purposeful design choice to attract and accomadate a certain type of guest and provide a 'quality guest experience' - so if a couple's two year old damaged an artwork, the host guarantee scheme would not even entertain it.
Claims for extra cleaning costs are not entertained either if you clean up yourself - they only accept a claim if you hire a professional cleaning company and provide their quote on letterhead within 48 hours of check out or before the next guests checks in - so if you have a back to back check out 11am and check in 2pm - you have just 3 hours to put in a claim with quote and photographs - and actually to also get the work done by the external cleaning firm before the next guest checks in!
Overall, the key issue is safety. My property is accessed via a flight of decending steps making it problematic for mothers with baby equipment like pushchairs (and likewise impossible access for a disabled guest), I have floor to celing blinds with engineered pulley ropes - kids would love those, a retro style electric fire, regency fireplace with removable coals, a walk-in power shower far too strong for little ones and no bath nor baby bath. I have no beds suitable for children under the age of 10 and neither do i want to risk a child of bed wetting age doing so, regardless of mattress protectors, the cost of laundering it, the mattress topper, the bedding etc which could occur more than once during a stay. I have white carpets and high quality wool rugs including in the dining area that would cost far too much to have steam cleaned - and no time between guests to do so anyway.
This repeats I guess many points so many other hosts have made and over and over again to airbnb but they do not listen and i would argue that they are putting children at risk by insisting hosts take them in properties that the host has advised it simply not suitable for children. So if a child was harmed - who would take responsibility if the parents decided to make a claim for an injury? Airbnb forced the child on the host due to it's policies so it should accept full liability and likewise unequivocally for any damages and extra cleaning caused due to that child policy.
What their decision will lead to it's 000's of hosts now switching to a not suitable for infants and toddlers option - I already have that selected and I know so many other hosts are now switching not necessarily due to not being able to charge but due 0-2's not counting in the maximum number of guests count. And due to parents therefore having bed wetting age children share the expensive adult bed and quality linens provided. By including 'age' in the discrimination policy, hosts not allowing children could arguably be de-listed regardless of the safety and suitability issues of the listing itself and the invalidating of hosts insurance policies where numbers of maximum occupancy are exceeded.
End of rant - sorry.