No, it isn't as good as getting a lottery pick. A lottery pick produces for your team on an ELC and is not in the middle-end of their prime when you acquire them. You don't rebuild in free agency - that's not a thing. You rebuild through the draft. Stop with the comparisons to Edmonton and Buffalo. They are bad because they have bad management and have had bad management consistently. It has nothing to do with "tanking" and everything to do with how they decided to rebuild. Buffalo hit free agency so many times during their rebuild and failed every time - that's a lot more of the same thing that you are suggesting than it is what I am suggesting. Edmonton has only had bad GMs for however many years.
People keep saying this, that there are other ways to do it. It's funny that the only teams that have won since the lockout has all been VERY BAD at some point for quite some time and acquired at least 1 top 5 pick, and that at least 1 top 5 pick was in every cup winning team since the beginning of the lockout, except for Detroit, who had 2 #1 centers they drafted in round 7 and one of the greatest defenseman of all time - not exactly anything that can be replicated with ease.
This team has been around for almost 100 years and has 4 cups. not once have they tried to build a team by being very bad, and yet plenty of teams younger than us have more cups because they have. Why not try it?