Upgrades that increase spawn rate do nothing when you're just sitting at a hard cap of 75 max orbs. Game gets increasingly grindy, while upgrades continue to get less meaningful. At some point, the "points" required for upgrades become meaningless also, since it takes so long to tier-up. Also, I had an odd tier 2 orb just sitting around by itself when the lowest that could spawn were tier 4. Targeted merging is difficult when you're hitting a ball with another ball and relying on physics. It's fine until you realize you have to merge over 4,000 more balls in order to reach the next tier.... This game needs better tools/upgrades to deal with the scaling. It's fun for a bit, though.
Prestige at tier 25 is millions of merges. That's not going to be achievable unless you do one of a number of things: raise the hard cap to something a lot higher (possible lag at some point. My computer is ancient though and runs this game fine in a browser), raise the minimum tier that spawns each time you tier up (this could get boring though), or more reliably create situations for more frequent merging.
Instead of rationing out spinners, why not let us spend our points on whatever contraptions we want? This would allow for custom setups and make the game a lot more fun.