Yes, the ICMP response packets could still be skewed, and the effect you mention is definitely real, but on a good connection, usually there should not be much to drop at all, neither TCP/UDP traffic nor ICMP packets.
Doesn't matter what it uses (though by default MTR does use regular old ICMP Echo - you have to specify -u or -t to get it in UDP or TCP mode). When TTL expires it still requires an ICMP TTL Exceeded be sent, regardless of whether or not you were sending ICMP through it.
Traceroute implementations in general are probably telling most everyone in this thread a lot less than they think, even without icmp deprioritization being taken into account.
https://archive.nanog.org/meetings/nanog47/presentations/Sun... is worth a read for most anyone that's ever attempted to use traceroute to troubleshoot networking, because they're almost certainly doing it wrong.