This is just flat out false. Gemstone vendors were immediately available at the start of ShB and EW and so were the riding maps. They were rank 1 in ShB and Rank 2 in EW. Rank 2 is 10 fates. 10. Which is enough to get your fate challenge log entry done and get you the gemstones to buy the riding map.
Just a few examples pulled from the XIV wiki.
The only riding maps that were not available at the time of expansion release were the Stormblood area maps. Those were released at patch 4.4. But that's likely because they put work into making riding maps available for HW and ARR areas at launch of Stormblood. Which they were.
Should they have done that for the SB maps too? Yeah. But...I doubt that was some nefarious scheme to force people to buy the Fenrir.
I mean...yeah? But then again, this is seeming like a tall AF order these days.
A cosmetic mount and actual gambling functions are two VERY different things. The Fenrir is not mandatory to play the game. That's just a fact. Trying to equate it to gambling is just...kinda gross.
Careful. Don't break your back moving that goalpost.