I honestly have no idea why Skiff would be interesting for Notion. From what I can grasp the only Notion features overlap are Skiff Pages and perhaps Skiff Calendar.
Companies acquire other companies all the time. Notion surely thinks they can use something controlled by Skiff to make more money than by using its money another way. I expect Notion will use the acquisition of Skiff to start offering new services or improve their existing services in an attempt to increase their market share. They don’t need to have similar preexisting services or products in order to do that, and there is surely information we don’t know that influenced Notion’s decision (e.g. a new product developed in secret that was only disclosed due to Skiff’s interest in being acquired).
Companies acquire other companies all the time. Notion surely thinks they can use something controlled by Skiff to make more money than by using its money another way. I expect Notion will use the acquisition of Skiff to start offering new services or improve their existing services in an attempt to increase their market share. They don’t need to have similar preexisting services or products in order to do that, and there is surely information we don’t know that influenced Notion’s decision (e.g. a new product developed in secret that was only disclosed due to Skiff’s interest in being acquired).