It's not DS-Lite that does that, it's CGNAT. Unfortunately CGNAT on v4 is unavoidable, because there just aren't enough v4 addresses to avoid it, so although it

It's not DS-Lite that does that, it's CGNAT. Unfortunately CGNAT on v4 is unavoidable, because there just aren't enough v4 addresses to avoid it, so although it does suck a lot it's hard to blame ISPs for using it. It's just one of the consequences of v4 exhaustion. DS-Lite makes the situation better by giving you v6, which means you can still do inbound connections. If you just had CGNATed v4 with no v6, then you wouldn't be able to do that at all.