Exactly. When the ruling was made no voting method had delivered an Equally Weighted Vote ever. So "as nearly as is practicable" was good enough. In districting (what the ruling was about) a perfectly equal vote is impossible, because populations move and change faster than district lines, but in voting an equal vote is totally practicable.
Fargo, ND (thanks to the Center for Election Science) made history as the first election where an equally weighted vote was guaranteed to every voter, no matter how many candidates they might have one their side. No vote-splitting in the voting method itself! (Voters can obviously still refuse to coalition and be divided and conquered, but they can also choose not to be.)
So, since Fargo has done it, we have proven that an equal vote in the voting method itself is practicable. (Thank you CES!) The bar has been raised.
I'm not a lawyer or a legal scholar, but I'll lay out my understanding:
Wesberry v Sanders was a Supreme Court Ruling. That ruling, I think, hinges on 'one person, one vote', or actually 'one man, one vote' (but that's another can of worms).
Is 'one person, one vote' in the Constitution? My understanding is that it would have been if it were not for the "great compromise" which replaced the 'one person, one vote' concept with the familiar 'one state, 2 votes,' system we know all to well from the US senate and electoral college. (Article 5 of the constitution.) Still, each voter or each state is guaranteed an equal vote in the constitution and the equality of the vote is a fundamental concept.
IRV and FPTP do not ensure an equal vote for voters, or for states.
Per wikipedia, "The constitutionality of IRV has been subsequently upheld by several federal courts. In 2018, a federal court ruled on the constitutionality of Maine’s use of ranked-choice voting, stating that "'one person, one vote' does not stand in opposition to ranked balloting, so long as all electors are treated equally at the ballot."
The operative there is "so long as all electors are treated equally at the ballot." Voting method scholars know that all electors (voters) are not. Some will have their 2nd choices counted if their favorites are eliminated. Some will not. A voter whose ballot is exhausted is not equal to a voter whose ballot counts in the final round.
"In 1975, a Michigan court ruling declared that [IRV] did not violate the one-man, one-vote rule: ... no one person or voter has more than one effective vote for one office. No voter's vote can be counted more than once for the same candidate. In the final analysis, no voter is given greater weight in his or her vote over the vote of another voter."
In IRV, yes, no voter has a vote weighted more than 1, but some voters absolutely have their vote reweighted to 0 between the 1st round and the final round.