That's because some users think tiered link building is outdated and doesn't work anymore. It's probably newcomers who have high expectations and want to rank in a short period by doing nothing but clicking a few buttons on some "magic" tool. If you check subreddits about SEO, you'll see a lot of people blindly saying automation is dead, ranking is impossible, or it's not worth it. This happens every year with every change.
But luckily, there are still people who really know the game and play it well. You mentioned a very important point—no matter how many links we build, the link juice has to be passed around properly. Unfortunately, many GSA/automation users blindly build tier 2 links without even checking tier 1, and most of them give up after a few months, blaming the software or strategy.
I've been using GSA for almost all my projects with just 2 or 3 tiers, and it's working fine.
