Maybe it would be helpful for some to know exactly what you see at a glance. I claim that the statement is wrong.
I did not claim that a controlled residential ventilation system is mandatory. I wrote that it cannot be done without it, and this becomes clear when looking at the requirements of the KfW. Hopefully, the different calculation models on the path to a subsidized house will disappear with the introduction of the Building Energy Act.
The OP wants to build a massive KFW 55 house but leaves open how he envisions the envelope of his massive new building. Usually, either a wood pellet or biomass heating system or a heat pump is required. Most decide, due to the costs for a heat pump, usually an air-water heat pump. This choice alone is not sufficient to achieve eligibility for subsidies. More insulation (also below the foundation slab) must be installed, possibly a solar system for domestic hot water, not infrequently a better type of brick (in monolithic construction), and if a basement is planned, the costs increase substantially again. At the end of this list of measures, the new building is so airtight that it would be negligent to forgo a controlled residential ventilation system. In that case, one might as well opt for a controlled residential ventilation system (in the example, a combination of air-water heat pump + controlled residential ventilation), which is cheaper overall.
I would not do without ventilation in a modern new building but would also not want to build a KfW subsidized house. The effort is out of proportion to the expected savings in operating costs. Users of KfW subsidies like to suppress that it is not about promoting their personal project or conserving resources, but solely about putting additional money into the market. The beneficiaries are, above all, the manufacturers of insulation materials. The financiers support this covert economic subsidy because it reduces their liability risk. The sellers benefit because it puts more commission into their cash register.
Anyone who absolutely wants to build a KfW 55 house is wise to hire an independent energy consultant — one who is not brought in on the recommendation of their general contractor/contractor/builder. Then the confirmation of KfW 55 after completion of the construction measure will also work.