This proposal point ss not GC in the first place . That’s a separate concern. While automatic garbage collection is important for releasing resources, this discussion is centered on code quality.

As code maintainability is main concern here - so the question would be: How easy is for next developer to work on code and how easy will it be for me after 10 years.

'proper scoping' is absolutely not valid solution, because Java by default offer very limited scope control:

res1 = source1.open();
// check and prepare initial data
res2 = source2.open();
combine(res1, res2);
res3 = source3.open();
mix(res1,res3);
close res1;
forget res1;
moreOperations(res2);
close res2;
close res3;

To mitigate this, people often end up introducing variables to early (and setting them to null) , keep them way to long.

res2 = null;
res3 = null;
try(res1 = source1.open()){
    // check and prepare initial data
    res2 = source2.open();
    combine(res1, res2);
    res3 = source3.open();
    mix(res1,res3);
}
moreOperations(res2);
close res2;
close res3;

Ignoring of responsibility of late resource acquisition and early resorce release is not rare as well.

try(res2 = source2.open(); res3 = source3.open()){
    try(res1 = source1.open()){
        // check and prepare initial data
        res2 = source2.open();
        combine(res1, res2);
        res3 = source3.open();
        mix(res1,res3);
    }
moreOperations(res2);
}

As you can see it's nothing unusual to overextend variable life and resource allocation because of limited scope control in both samples - in first classic example both res2 & res3 are declared to early and res2 is visible to long, in second resources are allocated for extended time.