Typically, many users are drawn to the Merged Cells feature in Excel, despite it having some significant disadvantages (especially related to copy/paste of ranges).
Frequently, Merged Cells are used in areas to group cells together visually, which can be done differently without causing the issues that merging does.
You can use an option within formatting called ‘Center Across Selection’ which takes the text from the leftmost cell of a range and centers it across the selected range.
Here is a screenshot of how to find it / use it by right clicking on a range and going to ‘Format Cells’. Then click the Alignment tab as shown below (the Center Across Selection option):
Voila! The text is centered across multiple cells without the need for merging them.
You can also remove the gridlines in Excel to make it look a bit cleaner.
That option can be found here under the ‘View’ tab: