I assume that you mean a hosts file that is configured to block known malware sites. In that case, yes, it is still helpful. The hosts file is the first place your computer looks for name resolution. Because this is first and local, it is very quick and adds very little overhead. This method prevents your computer from even requesting the harmful content, so your other malware tools don't even need to process anything listed in this type of hosts file. However, it is rather limited because it only applies to whatever known entries are listed.