While this is the correct reason sometimes, usually it isn't. They are intentionally losing trophies so that they can farm the newbies at the lower trophy level with their higher level troops. To intentionally lose, just drop 1 troops, and surrender the battle immediately. Higher level players with access to the Barbarian King or the Queen can drop that instead (out of range of any towers) and surrender immediately without the loss of that one troop.

Lots of players employ a technique called "lazy farming", where they look for bases where the collectors are scattered on the perimeter of the base and are half-full/full, and just throw down 50-100 archers to collect the resources in them. Repeat this every 5 minutes (since it doesn't take long to build 50-100 archers) and you collect resources very quickly. The loss of trophies is irrelevant, it is faster to farm for resources this way than building an expensive army to take on a higher level city.

The 1000-1250 trophy region is extremely ripe for "lazy farming", this is because the players there are trying to reach 1250 trophies to get the 100 gems achievement reward, and so they put their Town Hall in the center of their base to protect it, leaving the collectors on the perimeter. Farming towns on the other hand, always put the Town Hall on the perimeter so that people will kill it easily, granting 12 hours protection from further attacks - you lose way less resources this way, up to a maximum of 2 attacks on you everyday.