By the way I copy to you this first sentence.

But as everybody can read this first sentence is not the only one.

The first sentence introduce only the economic aspect:

Being open to any manufacturer allows many builders and sail makers to compete and so keep costs to a minimum.

Then, as I already write the most important is the limitation:

The Class remains aware to keeping development under control, maintaining a good balance between cost and performance. Corrected crew weights allows fairer racing with more ladies involved as helms and crews.

Nobody can ignore it now. That is the main difference between development class and Formula.
One time more (in red this time), the intentions of the class rules:

PART II – REQUIREMENTS AND LIMITATIONS

The intention of these Class rules is to ensure that the boats are as alike as possible in all aspects affecting performance as F18 is a Measurement Controlled Class. The crew and the boat shall comply with the rules in Part II when racing. In case of conflict Section C shall prevail.
The rules in Part II are closed class rules where anything not specifically permitted by the Class rules is prohibited.

A Olivier like to say: it is crystal clear