Nope, SARS and MERS are way deadlier than Covid-19, not just in initial estimates. South Korea tested hundreds of thousands of people and we have the Diamond Princess. That makes it unlikely that we are overestimating CFR by an order of magnitude due to uncounted mild cases. If you have someone reputable who thinks true CFR could be as low as 0.1%, please share! As far as I can tell no one believes it can be significantly below 1% for a country with similar demographics as the UK.