I'd love to hear the substantial difference between Clash of Clans selling you gems that make your building finish faster and LOL selling you XP boosts?
First off, i need to clarify how the two work, since they work substantially different to one another:
LOL boosts come in two variants, but the net effect is the same: XP income per time unit played is doubled. You can spend more money to have them apply to more time units played, but you can't increase the effects of the boosts. They do nothing else. (I assume rising in level also pushes one into higher level matches against stronger players.)
Meanwhile CoC gems do a multitude of things: They permit access to items that are otherwise inaccessible and increase competitiveness. They are very powerful multiplicators in allowing constructions times (that i assume to span days in the extreme) to be entirely removed. Lastly, they allow the player to ... play more by restoring heroes.
So, the practical effects are:
LOL XP boosts do not increase competetiveness of the player. In fact, they can detrimentally affect it by pushing a player into high level matches before they themselves earned the necessary experience to function well in them. Further, players are discouraged actively from spending too much on them, since they may be stockpiled, but not increased in power and past a certain amount of stockpiling it's senseless to buy more.
CoC gems increase competitiveness fo players massively, in some cases (build times) applying literally infinitely large multipliers compared to the x2 multiplied of LoL xp. Further they also serve lock the player out of playing the game unless the player spends real money to buy and spend them on healing their hero.
TL;DR:
LoL xp boosts are fixed subscription fees with a maximum cap.
CoC gems are literally consumable cheat codes designed to encourage unlimited spending.
That sure is a lot of words trying to disguise the fundamental truth that there is basically no difference between the effects of LoL boosts and gems. Both advance your summoner/base in exchange for money. They are both time "cheats"that you pay for to avoid a grind in each game.
You say flatly that 'LOL boosts do not increase competitiveness' but this is frankly completely false. An identical clone of myself playing on an account after $300 worth of xp and IP boosts will simply be much stronger than I am with f2p account. Eventually I may catch up but 'eventually' happens in clash of clans too.
LoL is capped at lvl 30. With boost, it will take you 1 week instead of 2 to reach lvl30. It does have any in game effect. Furthermore, they are not an item that you are trained to use as a currency.
The South Park episode about freemium game is very good at explaining how the freemium market model is based on addiction.
XP boost have no level after lvl 30, which is reached quickly, and is where the real game begins.
IP boost allows you to buy runes quickly, this happens outside the game. Runes have in-game effects, but the difference between T2 (which are extremely easy to buy without spending a dime) and T3 are minor.
I played LoL for years without spending a single penny in it, and I never were under the impression that the game was purposely made boring to force me to buy in-game items.
Freemiums game feels that way. At first, everyting is fun, and they even give you some 'free' currency to hook you on spending, and after a few hour, if you don't pay, the game becomes boring as fuck, because everything take hours.
Basically XP Boost is there for returning players.
Experienced players who want to create alternate account or those who move to another server.
It is there for convenience sake but Riot certainly goes out of its way to make creating a viable alternate account rather inconvenient. Being F2P I guess they have to have diverse revenue sources.
All this talk about "cheat" or "increasing competitiveness" is just nonsense.
I may be wrong in stating that XP boosts do not affect competitiveness, but the main point still stands: You only get to advance twice as fast with your 300$ in LoL compared to CoC where you can just blow all of your 300$ in a single day, hour even. There are several orders of magnitude between the two "eventuals" here. Additionally, not having XP boosts in LoL does not block you from playing, which CoC does. And lastly, not buying boosts does not lock any content away from you.
Then again, you haven't discussed in good faith from the get go (which is funny, since I primarily game on pc), so I expect you don't actually want to grok these differences.
