At some point in the past, there was no framework or library, then people distrusted them because REAL engineers knew the ins and outs of their language and knew best how to write the code for performance, then people began to embrace them in general, now there are so many variations picking the 'right' one can lead to paralysis.
The difference with these services as an extension of your codebase is that they cost a not insignificant amount of money. Typically, the frameworks and libraries we are used to cost nothing or a relatively small amount and then you're done writing checks.
Algolia, though a really neat product, would become very expensive very fast if you aren't careful, and I think you're going to find a lifecycle around these that involves using something like Algolia for something relatively hard to do well (search), then you will reach a point where you have to bring it in house or find something else due to cost.
Hopefully the team will have the resources to bring it in house in some fashion, but at some point, these services will not perform well enough for you or be so incredibly expensive that you have to move to something else.
That being said, these services are fantastic for people like me that love to build cool stuff and focus on the hard problem that WE want to solve, instead of all the hard problems in the world that must be solved to solve ours. Raising the chickens and grinding the flour vs. going to the store when baking a cake, etc.
I bring up Algolia because of my positive experience with them, they are a very nice service, quite easy to use, and just a generally pleasant piece of a tough project I had recently.