Big companies are not your worry in most cases. They have so much bureaucracy and internal politics that it's often cheaper for them to buy out the up-and-coming startups than it is to build in-house.
Instead, if you achieve success without much of a moat, you will be cloned by one of the "App Store mills". These are companies who employ multiple small teams (think 3-4 people), and each team is charged with cloning one of the most popular apps - they have really abbreviated development cycles, on the order of 6 weeks, and they just keep churning till they've drowned every app on the leaderboard in clones. And because they are astroturfing the whole space, they don't actually need most of these clones to be individually profitable.
Rocket Internet is often engaged in arbitrage where they bring an existing company’s idea to a different country or context. This is very different from the flood-the-zone astroturfing discussed above. Zalando is its own company employing ~5k engineers. This isn’t a copycat I would claim.
But maybe you’re referring to practices I am not aware of.
I worked for them: Its quuuiiiittteee different what they do from this "app-cloning-approach":
Rocket Internet copies business models and adapts them other countries. They are bringing in own people if they invest if required for the startup, but usually the companies are mainly built be the original founders with support from Rocket Internet on different layers (like legal).
Also Rocket invests Money. Sometimes .. a lot!
I worked for them and even interviewed to be founder of one of their spin-offs. GP’s comment has nothing to do with Rocket’s model. Zero.
And that’s coming from someone that despises Rocket for what they did to my workplace, the parent company, all teams I knew, and all colleagues I met from other projects.
App mills don’t respect anything at all, Rocket at least is Lawful Evil.
I personally think the hard part of building a SaaS app is not coding, it's understanding the complexities of a problem and building good abstractions to solve it. Code/software is the result, but certainly not the main challenge. And I think this reflects the time breakdown of good software engineers (mostly collaborating, brainstorming and designing interfaces vs. coding).
Instead, if you achieve success without much of a moat, you will be cloned by one of the "App Store mills". These are companies who employ multiple small teams (think 3-4 people), and each team is charged with cloning one of the most popular apps - they have really abbreviated development cycles, on the order of 6 weeks, and they just keep churning till they've drowned every app on the leaderboard in clones. And because they are astroturfing the whole space, they don't actually need most of these clones to be individually profitable.