You need to release your project as soon as possible for the lowest possible cost. Custom software would be too expensive, so you decide to go for an open-source solution. Along the way, you find out that you need more functions than you initially expected and that the sole open-source solution is not going to do the trick. Thank god there is a plugin for everything, right? Wrong!
Let me explain why you should (almost) never rely on plugins. There are many reasons why not to go down this road but here are the main three problems that you probably will have to deal with:
You will not be the owner of your system
From this point, all the other problems arise. If you want to run a web-based project, you need to know a lot about your system from the technical point of view. If you are relying heavily on the third-party software. If something changes in y, which always happens in business, there is a serious chance that you will not be able to change your app fast and without investing significant resources.
You will not be able to predict the future
You never know what will happen in a few months, especially in IT. Companies come and go, and even the biggest players on the field happen to kill their products without prior warning. The more reliant you are on an individual supplier, the worse your position is. Every new update of your system will be a nightmare, and you can only hope the new version of the plugins will be on time and without bugs.
No one will want to talk to you
The plugins will inevitably conflict with each other, and the same thing is going to happen with your suppliers. Being stuck among sever companies who always see the other party as responsible can quickly bring the project down in no time.
To be fair, this does not apply to every project. If you are sure that your business is not going to grow in the future, you can go for as many plugins as you want. The other scenario is a bit brighter — you can create your MVP like this if you do not have a problem with throwing most of the work away in the later stages, and starting all over again.