1 free night (of roughly the same value) for every 10 booked is very roughly the metric used for hotel programs too. But that's before any promos. The earning with promos (if you can stay to take advantage of the promos, that is) can be much higher. For example, 3/4 of the year Choice has a promo stay 2 separate times and earn 8000 points. $200+ hotels in Scandinavia are only 16k points typically, so if you're planning to go to Scandinavia, 4 cheap suburban stays at Comfort or Quality in the US will get you one free night at one of those expensivish hotels in Scandinavia. That's obviouslly way better than 1 free night (of the same cost) for every 10. But it only works for destinations in certain parts of the world as rewards stays, and only works for paid stays that are one night ("hotel hopping"). I'm just using it as an example of how much better than 1 free night (of the same value) for every 10 that you can get with a good promo at a hotel program. (Now, of course, not all promos are this good. But even a more typical "double points" promo changes the earning / redeeming ratio.)
It is true that no one hotel program covers the whole world well, and if you want to use hotel programs while roaming the wide world, you may need to belong to many of them (not just 2). For example, only Club Carlson, Choice and Best Western tend to be good useful in Scandinavia (beyond the capitals, anyway). But only Marriott (due to its purchase of Protea) is good in certain African countries. And only WynhamRewards is good in some cities in Argentina. Etc, etc.