Doodledog
Of course it's not unacceptable . If anything, using dryers is unacceptable as it uses power that could be saved. I use both, as well as an indoor heated airer, decision based on the weather and how likely it is to get things dry fairly quickly.
What is unacceptable, IMO is for a stranger to comment on your habits, particularly those you display in your own home, and even more so when she is a newcomer.
Oh, and the idea that hanging out washing is unhygienic is just ridiculous. Just ignore her.
Interfering old bat, you carry on and I hope the weather is with you. If that happened to me I would 'find' old tea towels, dusters, old shirts and sheets to put out every day that the weather was fine. Besides the sun makes things fresh, and bleaches out stains. I put some dust sheets out last summer after decorating, washed first, and after a day in the sun they were lovely, ready to fold and put away until next DIY.