Look up what Macro means Majinash and then you will realize why armies are required for it to be considered a real time strategy.
If armies are required for a game to be an RTS, are the games some other genre when a match starts? If I start with 5 villagers, or an MVC and nothing else, am I not playing an RTS?
It has nothing to do with "numbers", its to do with control, your controlling multiple area's on a map not a single laneway with a few mind controlled units that do "base attack damage" or maybe the one or two summons that do some form of mid-high tier elemental damage.
First: most mind controlled units don't do "base attack damage". The most boring of these is the alpha wolf, who has no active skills but has a massive 30% damage boosting aura around him. Other popular units include the Dark Troll Summoner, who has a net that roots someone to the ground (goes through magic immunity) and can raise skeletons if nearby units die. So now your mind controlled unit has summoned units. The Centaur has an AoE stun along with an attack speed aura. And Chen (a hero who can mind control up to 3 units at once) if played well can keep someone stunned for 6 seconds with these.
Second: all MOBA's I've played rely a great deal on controlling multiple areas on the map. Dota has two rune spots which every 2 min a rune will spawn at one, and much of the early game is spent keeping control of these at ever 2min mark to prevent the enemy from getting access to them. The Rosh Pit is an important area to keep control of, or the enemy might get access to the aegis. there are 3 lanes in most MOBAs (Steller Impact varies greatly by map, LoL has some 2lane play) with objectives in every lane, and most games also have jungles. In smite keeping control of the Jungle is incredibly important because it provides so much XP and gold. If you watch any pro DOTA you'll notice casters constantly talk about "map control" and how much vision a team has, on their side of the river and the other. If one team has no vision on the enemy side of the river and has lost a lot of map control due to the enemy taking objectives, the enemy team is much safer to collect resources on their side of the map, and even venture onto your side to take gold and XP your team needs.
Map control is HUGE in MOBAs, and to maintain it your team is often split up, doing different tasks in different places all at the same time.
I am going to take a guess that 0 of these games has summoning units spread over a different lane way while the main hero is fighting another area.
Then you would guess wrong. These games almost always involve that. Remember these aren't 1v1s, this is a 5v5 game. The split push (often referred to as "rat dota" by people who are defeated by it) is a strategy that involves using 4 members of your team to pressure the enemy on 1 front so they have to dedicate their focus to defending objectives there, while a 5th member who is either A: very good at quickly taking objectives, B: has a good escape in case the enemy team isn't distracted or C: both, will attempt to take an objective far away on the map on their own.
A great example is Phantom Lancer, who creates copies of himself (up to a dozen) who will send his army foward in 1 lane while he retreats safely to another lane or the jungle. Add this to your other 4 members pressuring another objective and now even if the enemy can defend against the 4 and the PL army, they still have to worry about Phantom Lancer separate from his army getting stronger because they can't pressure him.
Another example is Meepo who is literally 5 people. He clones himself as he levels up until you have 5 of the same unit. They share experience gained so most Meepo players spread them out, getting gold and XP from a jungle and a lane or two. Sounds like an RTS.
I also doubt summons are kept aside as reinforcements or as a ambush unexpectedly in some dark forest patch with f.o.w on. If so I would very much like to see some evidence.
This is exactly what Enchantress and Chen use their Centuars and Troll summoners to do. One player will attempt to move the lane back closer to their own tower, to force the enemy to advance foward (into a less safe position) and an Enchantress or Chen (who spent the early game often hiding in the jungle gaining experience there, where the enemy doesn't know their movements) will come behind their enemy, who has advanced into a risky position, and use the troll warlord to net the enemy, rooting them in place so that they cannot escape the attack.
They hide in the fog while a teammate lures the enemy into a risky position in an attempt to flank them. In this specific example they use a summon (actually a mind controlled monster from the jungle) to provide a means to prevent the enemy from fleeing.
You need to understand that even if you control only 1 unit, your team is more than 1 unit. You have an army in these games, you just also have 4 other humans helping you play it.