Transparent proxies aren't designed for anonymity.
However, you seem to be implying that this is by design and in fact not a bug. Is this an accurate conclusion?
SOCKS4a and SOCKS5 are designed to be used in environments where, in addition to direct connections, DNS also does not work.
There is no point in making the user wait for the DNS request to time out, when the user already specified to be in such an environment by selecting SOCKS5.
