100% agree. We are property managers, and this has caused us serious problems this year, including guests arriving with more people than the property is permitted to host (we have strict licensing in Andalucia), and/or arriving with Children younger than minimum age permitted at the property.
Owners and property managers do not add these conditions for the fun of it, as they are placed on us due to legal requirements or the community rules, etc.
This causes huge aggrevation for both the host and the guests, and the last thing a guest needs is to arrive at the property and be rejected entry because their child is too young, or their reservation does not meet thee "Community" rules (arrival time, property insurance age restriction, etc.).
What is also unhelpful, is AirBnB stating "Children under the Age of 2 go for free". Fine we do not charge extra for them, but a) we need to know they are coming before guests arrive as the maximum number of guests are applied irrespective of their age, and b) some properties are completely unsuitable for under 2-year olds, hence the insurance excludes hosting of this age group. Try arguing that one with an insurance company when there is a public liability claim!