In the past year, I've flown >100 times, 200k "butt-in-seat" miles, all long-haul in first or business class, spent 150+ nights in luxury hotels. I've flown around the US in private jets. I have millions of points and miles. I don't dare imagine what the retail cost would've been—but I pay a tiny tiny fraction of the price. Travel in that style is a hobby and I go out of my way to fly new airlines (I've tried long-haul first class on almost every reputable airline) and visit new places (40 countries and counting).
Getting really good at this, however, is a ton of work. It's a time-consuming hobby. I have spreadsheets, scripts, crawlers, and private groups to trade info, miles, and favors. I'm constantly on the lookout for new deals and loopholes; and I know the ins-and-outs of airlines' and hotels' policies. I've put in my 10,000h.
The point is that sure; for me, TPG seems like child's play. A lot of the information is a bit inaccurate, and they're not entirely unbiased. But most people don't have the willingness or interest to put in the work required to be really successful at this hobby. For that majority of people, following TPG's advice will let them experience a taste of this lifestyle. It might be enough to take their fiancé on a first class luxury honeymoon to Japan. In my opinion, that's pretty cool…