EAC is one of the most laughably easy anti-cheats to bypass, but given all the Harem mode content is online-only, losing internet connection will deny you everything even without EAC.
They claim the in-game currency to unlock things won't be purchasable, but enforcing a grind is how every AAA publisher has created a problem so they can sell you a solution - like how Ubisoft sells "time savers" (exp boosters) to shorten their grind (technically not selling currency, still milking you for money though). Given how Helius has been chasing industry buzzwords like "games as a service", "season pass", and "cloud gaming", it wouldn't be surprising to see him chase other industry shit-tier practices.