I agree, if the lender makes cheaper credit available, and if borrowers are automatically provided with drops in their loan rates. If borrowers have to shop around for a better deal and pay fees in the process, this would dull the effect of a lower base rate.

Some other reasons that the ECB wishes to fight deflation are described here:

https://www.ecb.europa.eu/press/key/date/2016/html/sp160404....